Category 6™

How Much Will El Niño Help to Quench California’s Grinding Drought?

By: Bob Henson and Jeff Masters , 10:46 PM GMT on January 29, 2016

With hillsides greening up fast, and chunks of coastline falling into the sea, it’s obvious that generous rains (and mountain snows) have returned to large parts of California this winter. But it remains an open question exactly how much this winter will help the state recover from a brutal four years of drought.

We can thank El Niño for the moisture return. One of the three strongest El Niño events since reliable records began in 1950 is still keeping sea surface temperatures (SSTs) much warmer than average over the central and eastern tropical Pacific. Those warm waters will continue to generate showers and thunderstorms thousands of miles east of their usual equatorial home. In turn, that displacement will keep forcing the atmosphere to adjust in ways that reverberate for thousand of miles, including northward into North America.

Figure 1. Boulders help shore up the base of an eroding cliff below an apartment complex (top) that residents were forced to evacuate in Pacifica, Calif., on January 27, 2016. Crashing waves and powerful rainstorms during this El Niño winter have put homes perched atop coastal bluffs near San Francisco in danger. Image credit: AP Photo/Jeff Chiu.

In the United States, El Niño tends to produce a stronger-than-usual subtropical jet stream. On average, this leads to wintertime conditions that are wetter than average from California across the Sun Belt to the Gulf States, with drier-than-average conditions across the northern tier of states. Temperatures during a strong El Niño typically segue from a warm central and eastern U.S. in November and December to a mild north-cool south tendency in January and February. These temperature patterns have largely materialized, albeit with a lot of variability. There’s been no lack of Gulf Coast moisture recently--especially in southern and central Florida, where this month is among the soggiest Januarys on record in many locations. And after a fire hose of Pacific moisture drenched the Pacific Northwest in the autumn, northern and central California have done very well in January, as has the immediate San Diego area.

Snowpack in the Sierras best in four years, but California drought still dire
Snowpack in the Sierras is 115 percent of normal, said the California State Department of Water Resources on Tuesday. This is the highest since 2011, when the snowpack was at 129 percent. The Sierra snowpack is a critical source of water to the state, contributing about 1/3 of the state’s water supply. Key reservoirs in the northern half of the state are still quite low, but beginning to rise. For example, Lake Oroville, the State Water Project's largest reservoir, is at 60 percent of its historical average for this time of year. This winter’s rains are still a long way from putting a significant dent in California’s four-year drought, though; the latest weekly Drought Monitor for California (January 26, 2016) showed 40 percent of the state in the highest level of drought, “Exceptional”, down from 46 percent at the beginning of the rainy season four months ago.

Figure 2. Change in drought conditions over the Western U.S. for the three-month period ending on January 26, 2016. Washington has seen a dramatic improvement in drought conditions, but California has seen very little improvement in its four-year drought. Image credit: National Drought Mitigation Center.

Will February come through for Southern California?
One part of California has largely missed out on the El Niño bounty thus far: the hugely populated coastal strip from Santa Barbara to Orange County, including the Los Angeles area. After a relatively dry autumn, this area has seen only near-normal precipitation for the month through January 29. Experts on El Niño and regional climate have been urging Southern Californians to be patient for some time, and they’re largely adhering to that advice.

Using the two maps below, John Monteverdi (San Francisco State University) pointed out that the strongest El Niños tend to bring Southern California their heaviest rains in Feburary and March, rather than January. “What I conclude from this is that, so far, what has happened in January is basically what climatology said would happen,” Monteverdi said. “Now if February and March precipitation fails, then this strongest or nearly-strongest El Niño in the record since 1950 will have failed to produce the precipitation we expected.”

Figure 3. Left: Departures from average precipitation (in inches) for the 30-day period from December 28, 2015, to January 26, 2016. Right: Departures from average precipitation in January for the five strongest El Niño events between 1950 and 2014. Image credit: NOAA Regional Climate Centers (left); NOAA/ESRL/PSD and CIRES-CU (right); images courtesy John Monteverdi.

Figure 4. Departures from average in land and ocean temperature for December 2015. Darkest red indicates areas of record-warm temperatures. Image credit: NOAA/NCEI.

Looking at the global scale, what jumps out like a sore (red) thumb is the vast swaths of warmer-than-average temperatures across the world’s oceans, especially across the tropics and subtropics. “Things are very, very warm globally, and subtropical ridging has been unusually pronounced this year,” said Daniel Swain (Stanford University), author of the California Weather Blog. “This ridging includes the semi-permanent Pacific High, which has been largely responsible for keeping the storm track aimed at Northern rather than Southern California.”

Swain added: “On a basic level, warm El Niño forcing puts a lot of heat into the tropical atmosphere and ultimately causes strengthening/straightening of the Pacific jet. That has happened this year, though it has occurred 500 or so miles north of what many people were expecting--a small shift in subtropical ridging by global climate standards, but a critically important one if you happen to live in Los Angeles.”

What’s different about this El Niño
Every El Niño has its peculiarities, and the blockbuster event of 2015-16 is no different. Figure 5 (below) shows the SST departures for the six strongest El Niño events since 1950. One notable difference between the current event and past ones is the dramatically warmer Niño4 region--the westernmost area, far out in the equatorial Central Pacific. This toasty Niño4 helps explain the turbocharged Central Pacific hurricane season of 2015, which sloshed into January 2016 with the unseasonable development of Hurricane Pali--the first hurricane known to prowl within one of the Niño regions shown in the map. It’s not yet clear how the distinctive SST pattern of the Niño regions this winter is intersecting with other factors, including the widespread oceanic warmth elsewhere.

One thing is clear: this isn’t an El Niño Modoki. That subcategory of El Niño, whose downstream effects can differ from those of a “classic” event, is defined by SSTs that are above average in the central Pacific (Niño4) but below average in the far eastern Pacific (Niño1+2). Right now, the Niño1+2 region is still running well above average.

Figure 5. A look at temperatures in the four Niño regions of the equatorial tropical Pacific (see map at top) during the last six El Niño events classified as “strong” or “very strong”, including the current El Niño through December 2015. Years shown in each graphic are the beginning year of the event. Image credit: NOAA Climate Prediction Center (top), courtesy Jan Null, @ggweather (bottom).

Some hopeful signals for the weekend and beyond
The latest Pacific storm to approach California is trending southward in model projections, a good sign that the Los Angeles area has a shot at its healthiest rains in almost a month. Another good sign: this storm has a robust channel of moisture extending southwestward to the tropical Central Pacific. Local forecasters expect as much as 1” in coastal areas and up to 2” in the mountains and foothills, and those numbers may prove low. If this storm comes through as expected, it will bump the area up to well-above-average totals just in time to close out January. Things may quiet down again for the first few days of February, but that’s not so unusual for SoCal, where even a torrentially wet winter by local standards may see rainfall on only a few days.

In its most recent experimental forecast discussion for weeks 3-4, issued on Friday afternoon and valid for the period Feb. 13-26, NOAA points to model indications that the subtropical jet will undercut Pacific ridging and enhance the odds of above-average rainfall and snowfall over far Southern California and much of the Southwest. As shown in Figure 6 (below), the week 3-4 probabilities have that certain El Niño look to them.

We’ll have a new post on Monday. Have a great weekend, everyone!

Bob Henson and Jeff Masters

Figure 6. NOAA’s experimental extended precipitation outlook (departures from average) for the two-week period of Feb. 13-26, 2016. Image credit: NOAA Weather Prediction Center.

El Niño Drought

Winter Storm Jonas: Fourth Strongest Nor'easter since 1950

By: Jeff Masters and Bob Henson , 5:34 PM GMT on January 29, 2016

The massive blizzard that rocked the Mid-Atlantic and Northeast U.S. last weekend, killing at least 58 and leaving over $2 billion in damage, has been rated the 4th most severe snowstorm to hit the area in the past 66 years, said NOAA. A Category 4 or “Crippling” rating was given to the storm using NOAA’s Northeast Snowfall Impact Scale, also known as NESIS. NESIS scores are a function of the area affected by the snowstorm, the amount of snow, and the number of people living in the path of the storm. Wikipedia has a list of NESIS rankings based on the original scale (created by Paul Kocin and Louis Uccellini] as well as a revised version implemented by NOAA in 2005.

The only stronger storms on the NESIS scale since 1950, according to NOAA, were:

Category 5 - March 1993, Mid-Atlantic/New England
Category 5 - January 1996, Midwest/Mid-Atlantic/New England
Category 4 – March 1960, Midwest/Mid-Atlantic/New England

Insurance broker Aon Benfield said economic losses from the blizzard would likely be at least $2 billion, and added that a similar storm system in January 1996 caused $4.6 billion in losses.

Figure 1. Residents were forced to walk in the streets of Washington, D.C., during and after Winter Storm Jonas. Image credit: Joe Flood, NOAA.

Jonas also ranks high on NOAA’s Regional Snowfall Index
Another way to view Jonas is through the lens of the Regional Snowfall Index (RSI). According to NOAA’s National Centers for Environmental Information, NESIS “can be thought of as a quasi-national index that is calibrated to Northeast snowstorms,” whereas the RSI examines each region of the country independently.

On the RSI, Jonas ranks #6 out of the top 200 Northeast snowstorms since 1900, which is slightly lower than the NESIS ranking (again, only the Northeast region alone is considered when calculating this RSI value). Interestingly, when you look at the total area affected by snowfall over the Northeast region, Jonas was quite unimpressive: #199 out of 200! It was the large snowfall amounts and the large number of people affected that pushed up Jonas’s total RSI rating for the region.

For the Ohio Valley, the RSI for the Jan. 22-24 storm ranks #12 among the top 200 snowstorms, thanks to the heavy snows that struck Tennessee, Kentucky, Ohio, and West Virginia early on. For the Southeast region, the storm came in as #14 due to the heavy amounts in the higher terrain of North and South Carolina and across much of Virginia. Thanks to Stu Ostro, The Weather Channel, for background on the RSI.

Figure 2. Snowfall from Jan. 22 to 24, 2016, was spread across the the Ohio Valley, Southeast, and Northeast regions of the United States as defined in the Regional Snowfall Index (RSI). Image credit: NOAA/NCEI.

More reflections on the big storm
Steve Gregory has an a new Thursday post, Blizzard Overview and Why NYC Got Much More Snow Than Forecast, and wunderblogger Lee Grenci offers his thoughts on the storm in his latest post, Reflections on the "Blizzard" of 2016: A Rant about Transferring Energy to the Coast.

We’ll be back late Friday afternoon with an update on El Niño and California rainfall.

Jeff Masters and Bob Henson

Winter Weather Extreme Weather Extreme Weather

Climate Science Legal Defense Fund Celebrates its Four-Year Anniversary

By: Jeff Masters , 8:03 PM GMT on January 28, 2016

Whenever scientific research uncovers truths that threaten the profits of large and powerful corporations, those companies--and the politicians these corporations' money help elect-- inevitably fight back by attacking the scientists. As I discussed in detail in my 2009 blog post, The Manufactured Doubt industry and the hacked email controversy, we've seen this behavior most clearly with the tobacco industry, but manufacturers of chlorofluorocarbons, asbestos, benzene, beryllium, chromium, MTBE, perchlorates, phthalates, and a slew of many other toxic chemicals have all waged elaborate campaigns to attack the scientific findings and the scientists that threatened their profits. These attacks often take the form of legal action, which government or university-funded scientists do not have the resources to combat. Such attacks against climate scientists have been particularly pernicious and numerous in recent years, and multiple climate scientists are currently involved in litigation in state and federal courts across the United States. The Climate Science Legal Defense Fund (CSLDF) was created to help these climate scientists fight back. CSLDF works to help raise funds for scientists’ legal defenses, serves as a resource in finding pro bono legal representation, and provides support during difficult litigation proceedings as well as when legal action is threatened. I'm proud to say that I'm a founding board member of the charity, and this week marks the four-year anniversary of their official debut. Over that time, they’ve helped nearly a hundred researchers across the country, from Arizona to Virginia. In celebration of their birthday, they’ve launched a new website at The new site explains their history, details their initial work defending Dr. Michael Mann, and describes their current projects. I hope you will consider making a donation to this worthy cause in the future.

Figure 1. Screen shot of the new website at

To learn more about the well-funded attacks on climate science and climate scientists by the fossil fuel industry, my fellow CSLDF board member, Noami Oreskes, has co-authored the excellent book, Merchants of Doubt, which has also been made into a fascinating documentary (available on Netflix.)

My next post will be Friday afternoon.
Jeff Masters

Climate Change Politics

Sixteen National/Territorial All-Time Extreme Heat Records Set in 2015

By: Jeff Masters , 4:23 PM GMT on January 27, 2016

In addition to being the warmest year on record when averaged over the entire globe, 2015 was also notable for all-time extreme heat records. Sixteen nations or territories tied or set all-time records for their hottest temperature in recorded history in 2015, and two (Israel and Cyprus) set all-time cold temperature records. For comparison, only two nations or territories set all-time heat records in 2014, and nine did in 2013. The most all-time national heat records held by any year is nineteen in 2010. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. I use as my source for international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Wunderground's weather historian Christopher C. Burt maintains a database of these national heat and cold records for 235 nations and territories on's extremes page.

Notable global heat and cold records set or tied in 2015
Hottest temperature in the world in 2015: 52.8°C (127.0°F) at Mitribah, Kuwait on July 30
Coldest temperature in the world in 2015: -82.9°C (-117.2°F) at Dome Fuji, Antarctica, September 13
Hottest temperature in the Southern Hemisphere in 2015: 49.2°C (120.6°F) at Reobourne Airport, Australia, February 21
Coldest temperature in the Northern Hemisphere in 2015: -63.8°C (-82.4°F) at Geo Summit, Greenland, December 16

Number of major worldwide stations with at least 40 years of records that recorded their highest all-time temperature in 2015: 293 (for comparison, this number was 198 in 2014.)

Number of major worldwide stations with at least 40 years of records that recorded their lowest all-time temperature in 2015: 13 (for comparison, this number was 15 in 2014.)

- On February 21, Wittenoom, Australia recorded a minimum temperature of 35.1°C, which is a new world record of highest minimum temperature for the month of February.

- On March 24, Esperanza Base recorded 17.5°C, which is the highest temperature ever recorded in the Antarctic mainland and second in Antarctica only to the Signy Island record of 19.8°C. Signy Island is located far away from mainland Antarctica, and is just below the conventional latitude of 60°S.

- On July 26, Geo Summit in Greenland recorded -30.7°C, which is a new record of lowest temperature ever recorded in July in the Northern Hemisphere (at any elevation). Previous record was -30.5°C at the Mt McKinley AWS, Alaska, U.S.

- On August 27, Geo Summit in Greenland recorded -43.5°C, which is a new record of lowest temperature ever recorded in August in the Northern Hemisphere (at any elevation). Previous record was -43.4°C at Cathy AWS, Greenland.

- On October 24, Geo Summit in Greenland recorded -60.0°C, which is a new record of lowest temperature ever recorded in October in the Northern Hemisphere (at any elevation). Previous record was -57.8°C at Northgrip, Greenland.

- On October 27, Vredendal in South Africa recorded 48.4°C, which is a new world record of highest temperature for the month of October.

- For the year, Coro in Venezuela recorded a yearly average temperature of 30.5°C (86.9°F), which is the hottest ever recorded anywhere in the Americas. It is also one of the highest average yearly temperatures ever recorded in the world outside the area of the Red Sea (lowlands/depressions/coasts of Ethiopia, Eritrea, Djibouti, Somaliland, Saudi Arabia, Yemen). Outside of that area, only Bangkok Klong Thoey Station had a higher yearly average temperature: 30.7°C in 1998.

All-time national and territorial heat records set or tied in 2015
French Guiana set its national heat record on November 3, when the mercury hit 37.9°C (100.2°F) at Saint Laurent du Moroni.
Indonesia tied its national heat record on October 28, when the mercury hit 39.5°C (103.1°F) at Semarang Airport.
Anguilla set its national heat record on October 10, when the mercury hit 34.2°C (93.6°F) at The Valley Airport. This was the 3rd time in 2015 Anguilla broke its all-time heat record.
Saint Barthélemy set its national heat record on October 5, when the mercury hit 35.5°C (95.9°F) at Gustavia.
Dominica set its national heat record on October 4, when the mercury hit 35.5°C (95.9°F) at Canefield Airport. That tied the record set the previous day.
The U.S. Virgin Islands set their national heat record on September 11, when the mercury hit 35.6°C (96°F) at Charlotte Amalie Airport. Note: the unofficial record listed by NOAA for the U.S. Virgin Islands is 99°F at the Charlotte Amalie Airport in 1988, 1994, and 1996. Mr. Herrera has researched the history of temperature measurements in the islands, and found that data taken at this airport was generally reliable after 1998 and before 1972. Between 1972 to 1998, the data was seriously flawed, with minimum temperatures up to 20°F from the real temperature.
Hong Kong set its national heat record on August 8, when the mercury hit 37.9°C (100.2°F) at Happy Valley.
Germany set a new national heat record of 40.3°C (104.5°F) twice in 2015: on July 5 and on August 7, both at the Kitzingen station in Bavaria.
Vietnam tied its national heat record of 42.7°C (108.9°F) at Con Cuong on May 30.
Palau tied its national heat record of 34.4°C (94.0°F) at Koror Airport on May 14.
Venezuela set a new national heat record of 43.6°C (110.5°F) at Coro on April 29.
Laos tied its national heat record of 42.0°C (107.6°F) at Thakhek on April 20.
Ghana set a new national heat record of 43.3°C (109.9°F) at Navrongo on April 10. This was the third time in 2015 that Ghana tied or set a new all-time heat record.
Cocos Islands (Australian territory) tied their all-time heat record with 32.8°C (91.0°F) on April 8.
Equatorial Guinea set a new national heat record of 35.5°C (95.9°F) at Bata on March 18.
Wallis and Futuna Territory (France) set a new territorial heat record with 35.5°C (95.9°F) on January 19 at Futuna Airport.

Special Mentions:
Antarctica set a new heat record for its mainland of 17.5°C (63.5°F) at Esperanza Base on March 24. Previous record: 17.4°C (63.3°F) at Marambio Base, set the previous day. The World Meteorological Organization (WMO) has appointed a committee to study this event and determine if this represents an official record for the continent. Note that this is a record for mainland Antarctica, not a territorial or continental record. The all-time maximum record for the continent and territory of Antarctica is 19.8°C (67.6°F) on January 30, 1982, in Signy Island, South Orkney, an island group located about 450 miles northeast of the tip of the Antarctic Peninsula, the northernmost portion of mainland Antarctica. Geologically, the South Orkney are on the Antarctic plate, and politically, they are part of Antarctica.

Switzerland had its highest reliably measured temperature on record in Geneva on July 7, when the mercury hit 103.5°F (39.7°C). The only higher temperature ever measured in the country was a 106.7°F (41.5°C) reading on August 11, 2003 at Grono. As reported at the Swiss news site, this old record was achieved "using an old measurement technique of weather huts, which generally recorded temperatures a few degrees higher than modern instruments." Weather records researcher Maximiliano Herrera agrees that this year's 39.7°C reading in Geneva is the highest reliably measured temperature ever in Switzerland, though the August 11, 2003 temperature at Grono was probably warmer (near 40°C), after correcting for the known problems with the site.

Samoa was originally listed by Mr. Herrera as tying its national heat record with 36.5°C (97.7°F) on January 20 at Asau, but a subsequent review of the record revealed possible issues with the measurement equipment, so this record is dubious.

All-time national and territorial cold records set in 2015
Israel set a new national cold record of -14.2°C (6.4°F) at Merom Golan on January 10.
Cyprus set a new national cold record for an inhabited place of -10.7°C (12.7°F) at Prodromos on January 9.

Special Mention:
Oman set an unofficial all-time cold record of -9.7°C (14.5°F) on January 20 at Jabal Shamas. The station is located on the top of a mountain above 3000m with no living population, and its time series is very short. Therefore, the record should be considered unofficial. The lowest temperature ever recorded in Oman in any representative station is -3.6°C (25.5°F) recorded at Sayq on January 26 1983. 

A big thanks goes to Maximiliano Herrera for providing the information in this post.

Jeff Masters

Heat Climate Summaries

Freakish Sleet, Snow, and Cold Sting Southeast Asia

By: Bob Henson , 5:21 PM GMT on January 26, 2016

At least 87 deaths have been reported from a cold wave over the last week that’s brought dangerously chilly temperatures and wintry precipitation to tropical and subtropical latitudes of Southeast Asia, as well as brutally frigid readings further north. The culprit is a southward extension of the upper-air circulation that rings the Arctic (a.k.a. the “polar vortex”), which allowed an unusually strong Siberian surface high to build southeastward (see Figure 1). In the northern part of Inner Mongolia, an autonomous region of China, the city of Genhe came close to its all-time low of –49.6°C on Thursday, January 21, when it dipped to –47.8°C (–54.0°F). At least 24 locations in China reportedly hit all-time lows between Friday and Sunday.

The greatest risk for casualties from this cold wave is at lower latitudes, where warm clothing and home heating are less common and people are less adapted to sudden chill. The 85 deaths above were reported from Taiwan, where many victims were found inside unheated structures. By Tuesday, readings in Taipei had not cracked 10°C (50°F) for a full three days, with nights dipping as low as 4°C (39°F). Two other cold-related deaths have been reported in Thailand, and that number could rise sharply.

Figure 1. An intense surface high boasted a central pressure of at least 1066 millibars at 0700Z Saturday, Jan. 23, 2016. The frigid high sent cold air cascading across the continent to the lowlands of Southeast Asia. Image credit: Thai Meteorological Department, courtesy Christopher Burt.

Snow on the South China coast
Snow is virtually unheard of across Southeast Asia, even at elevation, so the last several days have given millions of people their first-ever glimpse of the white stuff. On Sunday, the city of Ghangzhou, China (metro population 23 million) saw its first snowfall since at least 1949, when the People’s Republic of China was established. “Most [residents] had never before experienced snow,” reported the Hong Kong Standard. “People living on Beijing Road in Yuexiu ran excitedly from their homes to take pictures. Children opened their mouths to catch snowflakes.” According to weather records researcher Maximiliano Herrera, this may have been Guangzhou’s first snow since 1893, when six inches fell.

Just across Kowloon Bay, temperatures in Hong Kong plummeted to 3.1°C (37.6°F) on Sunday, the coldest reading observed there since 1957. Schools were closed on Monday due to the intense chill, and social media outlets were filled with reports of snowflakes, although the Hong Kong Observatory reported that the event actually consisted of “rain with small ice pellets.” About 40 miles to the west, the island of Macau--the world’s most densely populated urban area--reported its first occurrence of snow since 1893, according to Herrera. At Macau International Airport, WU’s daily weather summary for Sunday shows several hours of ice pellets.

The big chill in Thailand
WU climate historian Christopher Burt gave us an update from northern Thailand’s largest city, Chiang Mai, located at latitude 18.8°N and an elevation of 1020 feet. The average high and low for January 26 in Chiang Mai are 87°F and 60°F. “It is the daytime cold temperatures here that are probably unprecedented, not the daily low temps,” he told me. “We went from a monthly record high of 36°C [96.8°F] on Saturday to 90°F at noon on Sunday to 55°F with rain at noon on Monday, an amazing drop in 24 hours for this neck of the woods. Today [Tuesday] it was 52°F and drizzling at noon. Our high for the day was 54°F, the coldest daily max in memory for the area. It seems virtually certain that snow must have been falling in the mountains of northern Thailand above the 1500-1800 m level [around 5000-6000 feet].” Herrera noted: “On Tuesday the max temperature was higher at Tafjord, Norway, than in Chiang Mai, Thailand…in January!”

Snow has never been confirmed to fall in Thailand, even in historical records dating back to the 1600s, according to Burt and Herrera (although hailstorms do occur). Likewise, the mountains of Laos have never officially reported snow cover. Brief flurries were reported in Laos on Tuesday down to elevations below 1000 meters (3300 feet), according to Herrera. Both Thailand and Laos might have received accumulating snow at high elevation on Tuesday--although if the snowfall were brief and limited to sparsely populated areas, it might have gone undocumented even if it did occur. Temperatures across Southeast Asia should be rising dramatically over the next couple of days, as the air mass aloft is already warming.

Figure 2. Visitors check out snowfall at Yangmungshan National Park near Taipei, Taiwan, on Monday, January 25, 2016. Image credit: Billy H.C. Kwok/Getty Images.

Further north, in mountainous Taiwan, measurable snow fell at altitudes as low as 500 meters (1600 feet), prompting many residents to head for the hills for a rare peek at a fleeting winter wonderland. Just outside Taipei, the higher elevations of Yangmingshan National Park reported 5 cm (about 2”). Snowfall was also widespread in Japan, with even the far-southern island of Amami-Oshima reporting its first flakes in 115 years. An all-time record low of 5.2°C (41.4°F) was reported on Sunday at Kume Island, Okinawa, where “sleet” was recorded for the first time in 39 years. (Note that in the United Kingdom and many other countries, the term “sleet” refers to rain mixed with snow.)

Several other countries in the region have been affected by record cold and historic snowfall, according to Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. We’ll provide an update on this historic event in a subsequent post.

Bob Henson

Winter Weather

Colossal Nor’easter Dumps Record Snow from Maryland to New York

By: Bob Henson , 6:23 PM GMT on January 24, 2016

A ferocious, long-lasting winter storm took its parting swipes at the Eastern Seaboard on Saturday night, leaving in its wake a pile of snowbound cities and shattered records. Millions of people in the nation’s most densely populated urban corridor saw snowfall amounts that matched or exceeded the largest amounts observed in more than a hundred years of recordkeeping. It’s surprisingly difficult to measure snow in an accurate and consistent way, so you should keep a mental asterisk pinned to the statistics you’ll be seeing. Nevertheless, there is no question that this nor’easter, dubbed Winter Storm Jonas by the Weather Channel, was one for the ages--among the most powerful and far-reaching in regional history.

Figure 1. A woman walks down a snow-covered street in Brooklyn on Sunday morning, January 24, 2016. Most of New York City’s streets were cleaned up overnight after a huge snow storm slammed into the Mid-Atlantic states. Image credit: Michael Heiman/Getty Images.

Figure 2. Estimated snowfall totals from Winter Storm Jonas for the period Jan. 21-23, 2016. Image credit: The Weather Channel.

A sheaf of 24-hour and storm-total records
Even as the last flakes were flying on Saturday night, a number of sites with century-plus weather histories had already notched the most snowfall ever recorded for a single storm, and/or the most ever measured in a 24-hour period. Here’s a sample of preliminary data through Sunday morning. (Thanks to Alex Lamers, NWS/Tallahassee, for digging up some hard-to-find data on previous record storm totals in the NYC area). Note that the readings below generally pertain to snowfall measurements taken during the storm and added together, with a snow measuring board (snowboard) cleared off between each reading. The final snow depth, or the amount you’d measure by sticking a ruler (or yardstick) in the snow at the end of the storm, would normally be a bit less than the amounts shown below, because of the more recent snow on top compressing the lower, earlier layers. Decades ago, snowboards were used less frequently or were cleared less often when used, which means that some past storms would yield higher snow totals if measured with today’s standard techniques.

New York, NY (Central Park)
--Calendar-day total: 26.6” (old record 24.1” on Feb. 12, 2006)
--Storm total thru Sun. AM: 26.8” (record 26.9” on Feb. 11-12, 2006)

New York, NY (LaGuardia)
--Calendar-day total: 27.9” (old record 23.3” on Feb. 12, 2006)
--Storm total thru Sun. AM: 27.9” (old record 25.4” on Feb. 11-12, 2006)

New York, NY (Kennedy):
--Calendar-day total: 30.3” (old record 24.1” on Feb. 12, 2006)
--Storm total thru Sun. AM: 30.5” (old record 26.8” on Feb. 16-18 2003)

Newark, NJ:
--Calendar-day total: 27.5” (old record 25.9” on Dec. 26, 1947)
--Storm total thru Sun. AM: 27.9” (old record 27.8” on Jan. 7-8, 1996)

Allentown, PA
--Calendar-day total: 30.2” (old record 24.0” on Feb. 11, 1983)
--Storm total thru Sun. AM: 31.9” (old record 25.6” on Jan. 7-8, 1996)

Harrisburg, PA
--Calendar-day total: 26.4” (old record 24.0” on Feb. 11, 1983)
--Storm total thru Sun. AM: 30.2” (old record 25.0” on Feb. 12-13, 1983)

Philadelphia, PA:
--Calendar-day total: 19.4” (record 27.6 on Jan. 7, 1996)
--Storm total thru Sun. AM: 22.4” (record 31.0” on Jan. 6-8, 1996)

Baltimore, MD (Baltimore-Washington Airport and earlier sites):
--Calendar-day total: 25.5” (old record 23.3” on Jan. 28, 1922)
--Storm total thru Sun. AM: 29.2” (old record 26.8” on Feb. 16-18, 2003)

Washington, DC (Dulles)
--Calendar-day total: 22.1” (record 22.5” on Feb. 11, 1983)
--Storm total thru Sun. AM: 29.3” (record 32.4” on Feb. 5-6, 2010)

Washington, DC (National Airport and earlier sites):
--Calendar-day total: 11.3” (record 21.0” on Jan. 28, 1922)
--Storm total thru Sun. AM: 17.8” (record 28.0” on Jan. 27-29, 1922)

How widespread was the snow?
--This was the first storm on record to dump at least 24” of snow in both Baltimore and New York City, according to
--At least one location in all 21 New Jersey counties received at least 12” of snow.
--Snowflakes fell as far south as the Florida Panhandle on Friday night, and more than a foot of snow fell as far north as Massachusetts, giving this remarkable storm a north-to-south reach reminiscent of the even-more-sprawling Storm of the Century in March 1993.

Controversy in Washington, snowfall-style
As noted by Capital Weather Gang’s Angela Fritz, the readings at Washington National through Saturday evening struck many as being oddly low compared to neighboring reports, especially toward the north and west. The NWS plans to review the DCA snow reports, which were gathered by contractors for the FAA, a common practice at many airport locations. In a follow-up story on Sunday, Capital Weather Gang reported that the contractors at DCA had improvised and interpolated from snow-depth measurements after the on-site snowboard could not be found beneath the snow.

The WU almanac for Saturday at DCA shows that at 4:52 pm ET, Washington National reported 18” of snow on ground (rounded to the nearest inch), with 1” having fallen in the previous hour. Snow continued at DCA through midnight; however, the visibility jumped from just 1/16 mile at 4:52 pm to much higher values after that point (1/2 mile at 5:39 pm, and 1.75 mile at 6:49 pm), which is consistent with snowfall becoming much lighter.

On Sunday morning, CoCoRaHS reports of snowfall on the ground were all 20” or greater in the District and the adjoining western and northern suburban counties of Fairfax County, VA, and Montgomery County, MD. In the District itself, a snow depth of 22” was reported at the White House CoCoRaHS station, about 4 miles north of the airport and the closest station to DCA that filed a report on Sunday morning. Amounts were substantially lower just east and south of the District, in Prince George’s County, MD, and beyond, although very few of these were close to DCA. A snow-depth report of 16” came in from the vicinity of Fort Washington, about 8 miles south of DCA. To me, the CoCoRaHS data on snow depth imply that the DCA observations of total snowfall could be slightly on the low side but not too far out of line. It will be fascinating to see what the NWS concludes. Perhaps the bigger question is whether reports from DCA should be considered representative of the District, given that snowfalls are often significantly heavier as you go north and west.

Figure 3. Residents in Harrisonburg, Virginia, take to walking to their destinations amid heavy snow on Saturday, Jan. 23, 2016. Image credit: Daniel Lin/Daily News-Record via AP.

Figure 4. A van drives through a flooded street as ice and snow prevent drainage Saturday, Jan. 23, 2016, in Atlantic City, N.J. Image credit: AP Photo/Mel Evans.

Record storm tides along the southern New Jersey and northern Delaware coast
While most eyes were peeled on the big cities of the Northeast, coastal residents on either side of the Delaware Bay had to deal with major coastal flooding, especially during Saturday morning’s high tide. Storm-related surges of 4 to 5 feet were common across northern Delaware and southern New Jersey. These are close to the highest values one would expect in any nor’easter. To make matters worse, the full moon added about a foot to the normal morning high tide. The resulting storm tide (the amount over the typical low tide, or mean low low water, including both astronomical and storm-related effects) hit a record 9.27 feet at Lewes, DE, beating the 9.20 feet observed in the nor’easter of March 6, 1962. Cape May and Stone Harbor, NJ, both saw record storm tides that exceeded the values observed during Hurricane Sandy in 2012. Floodwaters poured into Stone Harbor in dramatic fashion on Saturday morning.

North of Atlantic City, the storm surge fell far short of the values observed during Sandy. The circulation around Sandy (which made landfall near Atlantic City) drove far larger storm surges of 10 feet or more into the coasts and bays of northern New Jersey and New York, resulting in storm tides as high as 15 feet. Moreover, Sandy’s huge waves--much bigger than those from Jonas--added greatly to the impact of the storm surge throughout the region. “Waves can contribute 50% or more to the coastal flooding along the open coastline and these are not included in storm tide measurements,” says Michael Lowry (The Weather Channel).

Widespread power outages
As of Saturday, more than 200,000 homes and businesses had lost power due to Jonas, although outages in the blizzard-socked areas were not nearly as widespread as had been feared. North Carolina was especially hard-hit by power losses due to a glaze of freezing rain that fell early in the storm, topped by a coating of snow.

Figure 5. Duke Energy lineman Aaron Crisafulli (bottom) checks on the progress of his coworker Jason Pearce in his bucket truck Saturday, Jan. 23, 2016 as Pearce cut tangled ice-laden tree limbs from power lines in downtown Raleigh, NC. The men were spending a 16-hour day moving from trouble spot to trouble spot in Raleigh after a winter storm swept over the Triangle area Friday and Saturday. Image credit: Harry Lynch/The News & Observer via AP.

Hats off to the computer models and NWS forecasts
One can’t help but be impressed by the persistence and accuracy of the leading forecast models in predicting near-record snowfall amounts for days on end ahead of the arrival of Jonas. Early in the week, the GFS and ECMWF models correctly zeroed in on Maryland, including Washington, D.C., as a focal point for heavy snow around Friday/Saturday. This gave local forecasters the confidence to issue a blizzard watch on Wednesday morning, two full days ahead of the storm’s arrival. (The massive traffic tie-ups in the D.C. area on Wednesday evening were the result of a mere half-inch of snow from a separate storm that preceded Jonas, a vivid reminder that even minor-seeming winter weather events need to be taken seriously in urban areas.)

New York was a tougher forecast nut to crack. Models agreed that there would be a sharp cut-off to the northern edge of heavy snow, a feature common in nor’easters, but they disagreed on where that northern edge would fall. As early as Wednesday, the NAM model was projecting huge weekend snowfall amounts in the New York area, while the GFS and ECMWF models tended to hold the heavy snow just south of New York, projecting only a few inches at best for the Big Apple. Forecasters at the National Weather Service’s local office in Upton, NY, wisely issued a prediction of 8-12” of snowfall and a blizzard watch on Thursday, just as blizzard warnings were being hoisted from Washington, D.C. to Philadelphia. In New York, this was the perfect situation for a watch, which is intended to alert the public that a particular outcome is possible but not guaranteed. As other models joined the NAM bandwagon on Friday, the blizzard watch for NYC was upgraded to a warning, which provided enough advance notice for city dwellers to stock up on provisions and city planners to prepare for the worst.

Figure 6. Low-, mid-, and high-end snowfall amounts (in inches--see legend at top) projected for the region around New York City as of 2 pm EST Thursday, January 21, 2016 for the period from 1 pm Friday to 7 am Sunday. The values at New York City ranged from around 2” at the low end to 20” at the high end.

Figure 7. Analysis of surface pressure and winds at 3 pm EST Saturday, Jan. 23, 2016, overlaid with radar returns from 3:15 pm EST. An occluded front (not shown) extends from the strong surface low just east of the Delmarva Peninsula to a secondary low extending off the east edge of the map. Image credit: NOAA Storm Prediction Center.

The storm ended up occluding in classic fashion, meaning that its main coastal surface low hung back while jet-stream energy carved out an occluded front extending northeastward just off the East Coast (see Figure 7). This evolution led to prime snowmaking conditions in a region of frontal formation aloft called a deformation zone that set up inland from the surface front, putting the heavy snow along and just northwest of the urban corridor. (Here’s an NWS explanation of deformation zones.)

WU blogger Steve Gregory, like many others, saw the classic nature of this setup emerging in the NAM and GFS models on Friday, although even then he wasn’t totally convinced. “Whenever a storm occludes out, it slows down and is pulled closer to the upper low (500 mb) and the storm track. Most importantly the deformation zone was then able to spiral further outward (northward) by 100-150 nautical miles, which brought very heavy snow bands into the NYC/Long Island/Cape Cod region,” Steve told me in an email. “This should NOT have been a surprise to me.”

Figure 8. A view of the sharp northern edge to snowfall across Pennsylvania, New York, and Connecticut, captured by the high-resolution MODIS satellite on Sunday morning, Jan. 24, 2016. Image credit: NASA (via Stu Ostro, TWC).

Figure 9. The sharp northern edge to heavy snow extended into central Pennsylvania. Image credit: NWS/Binghamton, NY (and a h/t to Stu Ostro, The Weather Channel).

The outer edge strikes again
Many New Yorkers remember the storm of late January 2015, when forecasters called for as much as three feet of snow in New York City, far more than actually fell there. Though that forecast might seem like a bust, the prediction of huge snows over much larger areas of eastern Long Island and southern New England actually proved correct. Again, the problem was a sharp cutoff to the heavy snow on the storm’s outer edge, with models disagreeing on whether that edge would end up west or east of New York City. NWS forecasters went big, then held off on dialing back the forecasts until it was abundantly clear that NYC would escape the worst.

It’s crucial that residents, businesses, and local government understand that some storms have a wider range of uncertainty than others at a given location. The experimental probabilistic guidance for snowfall that was posted on the home page of the NWS/New York office (see Figure 6) helped provide that sense. On Friday, it showed a low-end outcome of just an inch, but a high-end outcome of around two feet. I look forward to seeing this valuable tool become operational across the nation as soon as possible.

We’ll be back with a new post by Tuesday.

Bob Henson

Blizzard Winter Weather

Historic Snowstorm Takes Aim on Mid-Atlantic

By: Bob Henson , 10:40 PM GMT on January 22, 2016

It’s already been dubbed Jonas, Snowzilla, Make Winter Great Again, and no doubt some unprintable names, but the winter storm now spreading into the central U.S. East Coast is a formidable entity no matter what you call it. Our most reliable long-range computer models, the GFS and European (ECMWF), have been remarkably consistent all week in targeting the mid-Atlantic for the heaviest amounts. This storm will certainly rival some of the biggest mid-Atlantic storms in recent decades, and some model runs have cranked out snow totals beyond historical precedent. There is every indication that the GFS/ECMWF consensus is on the right track as this sprawling, dynamic system continues to take shape. Blizzard warnings are in effect for the heavily populated urban corridor from Washington, D.C., to New York, as well as from Long Island to Block Island, RI, and Martha’s Vineyard, MA.

Figure 1. Infrared image of Winter Storm Jonas as of 2015Z (3:15 pm EST) Friday, Jan. 22, 2016. Jonas is gradually taking on the comma-shaped configuration of classic East Coast winter storms. Image credit: NOAA/NESDIS.

Washington/Baltimore in the crosshairs
Snow began in the Washington area early Friday afternoon, just a bit sooner than expected, and was intensifying rapidly as rush hour set in. The snow will intensify tonight into Saturday and may continue into early Sunday, leading to some truly phenomenal totals throughout the D.C./Baltimore area. In its experimental probabilistic guidance, the local National Weather Service office lays the best odds on snow amounts in the immediate D.C. area in the vicinity of 24-30”, with the low- and high-end projections published earlier today ranging from 12” to 32”. If this storm produces as expected, it will rank as the city’s heaviest snow since the record 28.0” on Jan. 27-29, 1922 (see Figure 2 below), perhaps even topping that storm. Baltimore could top its all-time record of 26.8” set in the President’s Day 2003 storm (Feb. 16-18), and Dulles has a good shot at #2 behind the 32.4” observed during the Snowmageddon storm of February 5-6, 2010.

If this storm ends up toward the highest-end projections, we may have to go back to colonial days for a historical precedent. In his book “Early American Winters,” eminent weather historian David Ludlum chronicled the Washington-Jefferson Snowstorm of Jan. 27-29, 1772. The District of Columbia hadn’t yet been created, but future president George Washington measured snow at Mt. Vernon, VA, that was “full three feet deep everywhere.” About 100 miles to the southwest, another future president, Thomas Jefferson, called the accumulation “the deepest snow we have ever seen. in Albemarle it was about 3 [feet] deep.” Ludlum also cites the Maryland Gazette (Annapolis): “tis’ supposed the depth where not drifted is upwards of three feet, and it is with utmost difficulty people pass from one house to another.”

It’s worth keeping in mind that official snow measurements are carried out at regular intervals throughout a storm (as often as once each hour), with the snow measuring board cleared off every six hours. This means that at some locations, the total snowfall recorded during a storm will be more than the accumulation on the ground at any one time. Moreover, those snow-board clearings used to occur less frequently during a storm, which means that the total snowfall from some past storms may have been underestimated.

Figure 2. Top-ten snowfalls within a 72-hour period for Washington, DC; Baltimore, MD; and Dulles, VA. Image credit: NWS/Baltimore-Washington.

Further north, nagging uncertainty remains
Friday morning’s computer model guidance offered little help to forecasters in the New York area. Although the NAM model insists that accumulations well over a foot are possible from New York across southern New England, most models are calling for the storm’s heavy snow to have an extraordinarily sharp northern edge located across or very close to New York City. The experimental probabilistic guidance for NYC shows a range of possibilities from less than 1” to around 24”. This range actually isn’t much different from that in D.C., but because it starts at a much lower amount, the range of potential resulting impacts is far greater. Given that strong winds and at least some periods of heavy snow are a good bet, the New York City office opted to go with a blizzard warning. Note that a blizzard is defined not by snow amounts but by at least three hours of high wind (frequent gusts or sustained winds of at least 35 mph) and poor visibility (no more than 1/4 mile). These conditions could be met in or near New York City even if snowfall amounts are relatively low. Southern New Jersey and southeast Pennsylvania, including Philadelphia, are more likely to wind up on the south side of the sharp heavy-snow cutoff, putting them at risk for well more than a foot of snow. Update (5:59 pm EST]: NWS/New York City has raised its expected storm totals to 12-18" and sped up the storm's arrival.

Many other locations in the eastern U.S. are feeling the effects of Winter Storm Jonas, including:

Center, KY: 15” already on the ground late Friday
Nashville, TN: 5” already on the ground late Friday
Asheville, NC: 7-12” possible by late Saturday
Charlotte, NC: 0.1-0.2” of ice, topped on Saturday by 2-4” of snow and sleet (the storm is expected to clear in time for Sunday’s NFC playoff game)
Roanoke, VA: 11-21” possible by Saturday night

Top amounts recorded by late Friday afternoon included 15” at Center, KY, and 18” near the appropriately named Jonas Ridge, NC. Thanks to Nick Wiltgen and Dr. Greg Forbes (The Weather Channel) for these statistics.

What’s making this storm so powerful?
At Capital Weather Gang, Jeff Halverson has an excellent analysis of the factors leading into this remarkable storm, with the main player being a pronounced upper-level low over the Southeast that will trigger a surface low developing off the East Coast. The upper- and lower-level centers will align just east of the Delmarva in an occlusion, allowing the entire “stacked” system to slow down and prolonging the heavy snow. Also in the mix is a rich feed of moisture streaming up from the northern Caribbean, with pockets of as much as two inches of precipitable water (the amount that could be squeezed out above a given point). Temperatures are considerably warmer than average over the Northwest Atlantic, ranging from about 1°C above average near the Bahamas and northern Caribbean to 2-3°C above average off the Virginia coast northeast to the Canadian Maritimes. (Warmer-than-usual oceans are commonplace across the globe right now, as December was the warmest month in more than a century of global recordkeeping.)

Figure 3. Departures from average sea-surface temperature for this time of year, calculated for the week ending on Jan. 16, 2016. Image credit: National Hurricane Center.

Which of the factors driving Jonas is most unusual? Joe Romm (Climate Progress) and Andrew Freedman (Mashable) point out the strong, important links between rising global temperatures associated with human-produced climate change and the observed tendency for high-end precipitation events to become even heavier. Many of the record U.S. rainfall events over the past year have benefited from vast amounts of precipitable water, often at record amounts for the time of year. Winter storms rely on ample moisture as well as strong temperature contrasts and large-scale dynamics. In the case of Jonas, a crucial factor is the extreme intensity of the low-level jet stream pulling moisture from the Caribbean and slamming it around the north side of the surface low into the snow-generating machine over the mid-Atlantic. These powerful winds will replenish the atmospheric moisture being used up rapidly in the snow-making process.

I asked Richard Grumm, science and operations officer at the National Weather Service office in State College, PA, what he saw as the most noteworthy aspects of Winter Storm Jonas. He replied in terms of sigma levels, which express how often you’d expect a particular situation to recur based on previous weather patterns. A 2-sigma event (two standard deviations) occurs about 5% of the time at any given point, while a 6-sigma event is far more rare--in theory, a one-in-500-million likelihood, although the exact recurrence period for such extreme events is impossible to nail down. Grumm calculated sigma levels for the imminent storm using output from the GFS ensemble system (GEFS). Grumm noted that the precipitable water flowing into the storm is in the 1- to 2-sigma range: high but not extraordinary. However, the winds flowing from the Atlantic into the Delmarva peninsula about a mile above the surface could exceed 80 mph (see Figure 4). The east-to-west component of this wind qualifies as a 6-sigma event. Such anomalously strong winds, said Grumm, are “about as good as they get.” He added that 2012’s Hurricane Sandy was the last East Coast event to produce such a high-sigma east-to-west wind anomaly. The intensity of the upper-level front is also apparent in the very sharp south-to-north drop-off in heavy snow depicted by most models. The contrast between cold air over the Northeast and the unseasonably warm waters just offshore may help to enhance the front even further.

Figure 4. Winds at the 850-mb level (about a mile above sea level) projected by the 12Z Friday run of the GFS ensemble system (GEFS) for 7:00 am EST Saturday, Jan. 23, 2016. The lines at each point are directed into the wind; barbs along each line show the wind speed in knots (see this NWS guide). The colored areas denote estimated sigma levels (see legend at left) corresponding to the rarity of the east-west wind component. Higher sigma levels correspond to especially strong easterly or westerly wind components. Image credit: Richard Grumm, NWS.

Live-blogging the storm
As we move into the active phase of this blockbuster storm, it’ll be time to watch short-term mesoscale models more closely. These will help tell us where the most intense bands of snowfall will set up and how far that all-important northern edge of the storm will extend. Mesoscale snow bands can goose totals across southwest-to-northeast strips that may only be a few tens of miles across.

We’ll be documenting the progress of the storm through this weekend at our WU live blog. I’ll have another post by Saturday evening at the latest.

Bob Henson

Winter Weather Blizzard

All Systems Go for High-Impact Winter Storm across Eastern U.S.

By: Bob Henson , 9:18 PM GMT on January 21, 2016

Everything from tornadoes to paralyzing ice to blizzard conditions will be unfolding over the next several days as a massive storm system, dubbed Winter Storm Jonas by the Weather Channel, takes shape over the eastern half of the United States. Computer models have doggedly pointed to this scenario for the better part of a week, and the model consensus on the big picture continues to be unusually strong. The crosshairs for the heaviest urban snow appear to be on the Washington, D.C., area; more than two feet are possible there and nearby. Blizzard warnings were in effect Thursday afternoon in and near the Washington, D.C., area. The crystal ball is cloudier on where the storm’s north edge will end up--and that location is crucial, since it could be near New York City.

This sprawling storm is only now beginning to take shape across the South. Upper-level energy diving into the region will soon be cutting off from the main jet stream, leaving a powerful upper low in the Southeast that will move slowly northeast--in typical nor’easter fashion--along the East Coast. Along the way, a surface low located in northern Louisiana on Thursday afternoon will be succeeded by a new surface low predicted to develop just east of the Delmarva Peninsula by Saturday. That second surface low will team up with the upper-level low near the Gulf Stream and intensify rapidly over the weekend.

Below is a rundown of the key impacts expected from Jonas, followed by a closer look at potential snowfall amounts over the megapolitan area from D.C. to New York.

Figure 1. 24-hour odds of at least 0.25” of freezing-rain accumulation during the 24 hours from 06Z (1 am EST) Friday, January 22, 2016, to 06Z Saturday. Image credit: NOAA/NWS Weather Prediction Center.

Freezing rain and ice across mid-South
A large swath of the mid-South from eastern Arkansas to southern Virginia is in line for accumulations of ice on Friday into Saturday, as freezing rain develops on the north side of the still-evolving winter storm. The bull’s-eye for highest icing risk appears to be Charlotte, NC, where the timing could hardly be worse: the city is playing host to the NFC championship game on Sunday between the Carolina Panthers and Arizona Cardinals. Odds are better than even for Charlotte to get at least a half-inch of ice, which could be a devastating amount for this large urban area. Major disruption to game-related activities over the weekend is a strong possibility, and thousands of people planning to travel to the area for the game may end up disappointed by massive air and road gridlock across the East, although the worst of the storm will be over in Charlotte by the scheduled game time.

Figure 2. At midday Thursday, NOAA’s Storm Prediction Center was calling for an enhanced risk of severe weather through Friday morning along the central Gulf Coast, with a slight risk in northern Florida and southern Georgia later on Friday.

Severe weather along the Gulf Coast
Thunderstorms popped up on Wednesday night in Oklahoma atop low-level air close to freezing, a sign of the potent upper-level storm heading toward the East Coast. Storms were intensifying across northern Louisiana into north Mississippi on Thursday afternoon, and these should continue to work their way east across the lower Mississippi Delta through the evening. Low-level moisture is not quite as plentiful as it was during the holiday-week severe weather of late December, but very strong upper-level dynamics will largely compensate. High winds, large hail, and heavy rain are all possible, along with a few tornadoes. The risk of strong tornadoes appears relatively low. (Sharp-eyed scrutinizers of Figure 2 will notice the area of thunderstorms on Friday along the northern California coast, a region getting quenched this month by plentiful rain courtesy of Pacific storm systems.)

Figure 3. WunderMap depiction of surface winds at 8:00 am Sunday, January 24, 2016, based on the GFS model run from 12Z Thursday, January 21. Wind speeds are in knots; add 15% for miles per hour.

Coastal flooding along the mid-Atlantic
A coastal flood watch is in effect for the period from late Friday night to Sunday morning along most of the New Jersey and Delaware coast. WIdespread moderate flooding is expected, with some localized areas of major flooding. High waves of up to 15-20 feet just offshore will pound the coast, along with winds gusting to 50-60 mph or more. Beach erosion is a near-certainty, and some road and property damage is possible. The threat is being compounded by the full moon on Saturday night, which is adding 1-2 feet to the regular tidal cycle. The highest astronomical tide is on Saturday night, with tides about a foot less on Saturday and Sunday morning. Due to the storm’s timing, all three of these cycles could produce storm tides (astronomical + lunar + storm-driven) of around 7-8 feet across southern New Jersey and northern Delaware.

Storm surge expert Hal Needham has more on the coastal flood threat in a Thursday morning blog post. “I do not expect that this surge event will be one for the record books,” says Needham. “Although the winds will be howling from late morning until after dark on Saturday, the duration of this wind event will not be long enough to really get a big surge setup. So in places like coastal New Jersey, don't expect water levels to approach historical levels reached by Hurricane Sandy or even the 1962 Ash Wednesday Storm.”

Last but not least: Big snow for the Northeast urban corridor
Below are probabilistic maps drawn from several NWS offices, showing the low-end, mid-range, and high-end expectations for snowfall from this storm. By going to the higher-res versions linked from each caption, you can view the individual totals shown on the map--but it’s important to focus on the large-scale expected patterns of snowfall rather than the point-source projections.

Figure 4. Low-, mid-, and high-end snowfall amounts (in inches--see legend at top) projected for the region around Washington, D.C. as of 2 pm EST Thursday, January 21, 2016 for the period from 1 pm Friday to 7 am Sunday. For higher-resolution images, see the NWS/Baltimore-Washington website.

Washington, D.C. may end up with a truly historic snowfall. The mid-range amount shown below would be the city’s second heaviest on record, topped only by the Knickerbocker storm of 1922. Expect mesoscale banding to generate the heaviest snow in strips oriented from southwest to northeast. These bands could be only about 30-50 miles wide, but snow on either side would still be significant. There is some chance of a brief changeover to sleet toward the Delmarva Peninsula, but any changeover in or west of D.C. should not greatly affect snow totals.
From the NWS maps above:
Least to expect in D.C.: 8”
Mid-range: 24”
Worst-case: 33”

Figure 5. Low-, mid-, and high-end snowfall amounts (in inches--see legend at top) projected for the region around Philadelphia as of 2 pm EST Thursday, January 21, 2016 for the period from 1 pm Friday to 7 am Sunday. For higher-resolution images, see the NWS/Philadelphia website.

Philadelphia should have more trouble getting its second-highest storm total of all time than D.C., as its two highest amounts are 31” (Jan. 6-8, 1998) and 28.5” (Feb. 5-6, 2010). Compared to Washington, there is also more low-end uncertainty in Philly, but the area is still at high risk of a high-impact storm.
From the NWS maps above:
Least to expect in Philadelphia: 6”
Mid-range: 17”
Worst-case: 28”

Figure 6. Low-, mid-, and high-end snowfall amounts (in inches--see legend at top) projected for the region around New York City as of 2 pm EST Thursday, January 21, 2016 for the period from 1 pm Friday to 7 am Sunday. For higher-resolution images, see the NWS/New York City website.

New York City is perhaps the toughest forecast call of this event. The local NWS office issued a blizzard watch on Thursday, and it should be seen as just that: a watch, rather than a warning. Watches indicate where a particular event is possible, but not yet expected with confidence. As late as Thursday morning, there was huge model disparity in placing the north edge of the heavy snowfall, and that north edge will be a sharp one. As a result, New York City could get as little as a nuisance event or as much as a city-crippling storm. Subsequent model runs will be crucial in narrowing this range of uncertainty. Note that a blizzard is defined not by snow amounts but by at least three hours of high wind (frequent gusts or sustained winds of at least 35 mph) and poor visibility (no more than 1/4 mile). These conditions could be met in or near New York City even if snowfall amounts are relatively low.
From the NWS maps above:
Least to expect in New York: 2”
Mid-range: 12”
Worst-case: 20”

In summary...
All the ingredients are coming together for a blockbuster winter storm over the highly populated urban corridor from Washington, D.C., toward New York. The 0Z Friday suite of computer models tonight will be bolstered by data from dropsondes being released this evening by a NOAA Gulfstream-IV hurricane-hunter jet. Once we get to Saturday, short-range models such as the HRRR will become increasingly useful in pinning down the location of mesoscale bands as they evolve, as well as the crucial north edge of the storm.

I’ll be back with a new post by 3 pm EST Friday afternoon. We’ll also be launching a live blog tonight (watch our main WU page for a link) that will run through the duration of the storm. At 4 pm EST Thursday, WU meteorologists Shaun Tanner and Tim Roche will be joining me for a live-stream discussion of the storm on a special installment of “This Week in Weather”. You can watch the show and submit your questions through a link that’ll appear at show time on the This Week in Weather page. Don't forget to follow our Twitter and Facebook feeds too!

Bob Henson

Severe Weather Blizzard Winter Weather

Yearly, Monthly Heat Records Dissolve In 2015's Global Onslaught

By: Jeff Masters and Bob Henson , 2:04 AM GMT on January 21, 2016

The year 2015 ended in spectacular fashion, winding up as the warmest year in more than a century of recordkeeping--and it’s wasn’t even close to a photo finish. NASA and NOAA held a joint press conference on Wednesday to release their global climate assessments for the year. It had become obvious in recent weeks that 2015 was heading toward a new record high, but the final numbers were still startling. NOAA calculated that the average global temperature across both land and ocean surfaces for 2015 was 0.90°C (1.62°F) above the 20th-century average of 13.9°C (57.0°F). This makes 2015 the warmest calendar year, as well as the warmest of any 12-month period, in global temperature data going back to 1880. Using a slightly different technique, NASA confirmed that 2015 was the warmest year in this 136-year period.

The margin of 2015’s victory is itself noteworthy. NOAA calculated that 2015 beat the previous record warmth of 2014 by 0.16°C (0.29°F), which is the largest such margin for any year. NASA came up with a slightly smaller value--0.13°C (0.23°F)--which tied with 1998’s margin of victory.

Last year was the third-warmest on record for satellite-based estimates of temperature through the lowest five miles of the atmosphere, as calculated by the University of Alabama in Huntsville (UAH). Record warmth was recorded for autumn (September-November) as well as for December. Because these are indirect, large-scale estimates of temperature well above ground level, derived from satellite data, they need not correspond to trends in direct ground-based measurements of surface temperature.

Figure 1. Yearly global temperature (as expressed against the 20th-century average), 1880 - 2015. Shaded red bars indicate the average for each decade. Despite a relatively flat temperature trend in the first decade of the 2000s, global warming didn’t “stop” then. Each decade since the 1960s has been warmer than the prior one. Image credit: NASA/NOAA.

Figure 2. Departure of temperature from average for 2015, the warmest year for the globe since record keeping began in 1880. Image credit: National Centers for Environmental Information (NCEI) .

The role of El Niño
We can give El Niño credit (or blame) for part of this year’s record-smashing global temperature, but the shadow of longer-term warming due to human influence is inescapable. El Niño events tend to increase heat transfer from the ocean to atmosphere by spreading warm water across a broad stretch of the tropical Pacific, so as our climate warms, we can expect the biggest record-year spikes to occur during El Niño (as evident in Figure 2, below). That said, the huge margin of 2015’s record is comparable to the typical amount of global-scale warmth produced by a strong El Niño: several tenths of a degree Celsius. This means that 2015 may well have set a record even if El Niño were absent.

“2015 was remarkable even in the context of the ongoing El Niño,” said NASA/GISS director Gavin Schmidt. “Last year’s temperatures had an assist from El Niño, but it is the cumulative effect of the long-term trend that has resulted in the record warming that we are seeing.”

Figure 3. Departures from average in global monthly temperature from 1980 to 2015, with colors showing whether each month was characterized by El Niño (red), La Niña (blue), or neutral conditions. Image credit: NASA/NOAA.

What next?
The second year of a major El Niño tends to warm the global atmosphere even more than the first, as the atmosphere gradually adjusts to the ocean-surface warming. This means that 2016 has a very good shot at breaking the global temperature record that was just set by 2015, which in turn beat out 2014. Since records began in 1880, there have never been three consecutive record-warm years--another piece of evidence that long-term climate change is underpinning our current string of warmth. It would be exceedingly unlikely for El Niño to extend into 2017, so we might expect that year to break the string, but barring a huge volcanic eruption, the decade of the 2010s has an excellent chance of ending up warmer than the 2000s (see shaded bars in Figure 1).

The UK Met Office will soon be releasing its annual forecast of global temperature for the next decade (here’s the forecast issued in January 2015). As we discussed early last year, the now-positive state of the Pacific Decadal Oscillation suggests that we may have embarked on a decade or two of more-frequent El Niño events and accelerated atmospheric warming, similar to what occurred in the 1980s and 1990s. The PDO helps explain a good bit of the multidecadal variation in global temperature, including the slowdown in atmospheric warming evident in the 2000s and early 2010s. During these slowdowns, Earth’s oceans are taking up a larger fraction of the heat being trapped by human-produced greenhouse gases; during the speedups, the oceans are returning some of that heat to the surface. All the while, ever-increasing amounts of human-produced greenhouse gases are pushing up both the peaks and valleys of global temperature.

Earth's warmest December on record
In a fitting capstone to a sizzling year, December 2015 was the warmest calendar month in Earth’s 136-year temperature record, according to the NOAA/NCEI monthly recap released on Wednesday. December 2015 was the eighth consecutive month that a monthly high temperature record was set in NOAA's database. NASA also rated December 2015 as the single warmest calendar month in its database.

Figure 4. Departure of temperature from average for December 2015, the warmest December for the globe since record keeping began in 1880. Record warmth was observed over vast swaths of the globe, including far eastern North America, northern South America, southern Africa, and central and northern Europe, as well as most of the equatorial Indian Ocean and western North Atlantic. Image credit: National Centers for Environmental Information (NCEI) .

Arctic sea ice comes in at 4th lowest December extent on record
Arctic sea ice extent during December 2015 was the 4th lowest in the 36-year satellite record, according to the National Snow and Ice Data Center (NSIDC). An usual surge of warm air during the last week of December that brought temperatures above freezing close to the North Pole, and brought sea ice formation to a virtual halt. Arctic sea ice was close to a record minimum (for that time of year) going into 2016, possibly due to this warm surge.

Notable global heat and cold marks set for December 2015
Hottest temperature in the Northern Hemisphere: 40.6°C (105.1°F) at Armero, Columbia on December 26 and 31, and also at Guaymaral, Colombia on December 31.
Coldest temperature in the Northern Hemisphere: -63.8°C (-82.8°F) at Geo Summit, Greenland, December 16.
Hottest temperature in the Southern Hemisphere: 47.2°C (117.0°F) at Port Augusta, Australia, December 19.
Coldest temperature in the Southern Hemisphere: -43.1°C (-45.6°F) at Dome Fuji, Antarctica, December 1, and at Pole of Inaccessibility, Antarctica, December 2.

Major stations that set (not tied) new all-time heat or cold records (for any month) in December 2015
Queenstown (South Africa) max. 40.4°C  1 December
Estcourt (South Africa) max. 40.4°C 1 December
Belem (Brazil) max. 38.5°C 1 December
Caxias (Brazil) max. 42.7°C 2 December
Vryburg  (South Africa) max. 42.3°C 6 December
Van Zylsrus (South Africa) max. 43.8°C 6 December
Kuruman  (South Africa) max. 40.8°C 7 December
Frankfort  (South Africa) max. 38.1°C 7 December
Pretoria  (South Africa) max. 41.0°C 7 December
Ottosdal  (South Africa) max. 42.0°C 7 December
Rustenburg (South Africa) max. 39.4°C 7 December
Bethlehem (South Africa) max. 35.6°C 7 December (revised to 36.2°C on 24 December)
Cooma (Australia) max. 39.5°C 20 December
Ladysmith (South Africa) max. 41.5°C 24 December
Richard Bay (South Africa) max. 42.7°C 24 December
Cedara (South Africa) max. 40.4°C 24 December
Pietermaritzburg (South Africa) max. 42.1°C 24 December
Tigerhoek (South Africa) max. 43.2°C 30 December
Robertson (South Africa) max. 44.8°C 30 December

Kudos go to Maximiliano Herrera for supplying the data for the "Notable global heat and cold marks set for December 2015" and "Major stations that set (not tied) new all-time heat or cold records in December 2015" sections of the post.

Coming up: full coverage of the big mid-Atlantic snowstorm
We’ll have a full update Thursday afternoon on the mammoth winter storm that will be developing from the central Appalachians onward to the East Coast over the next several days. Computer models remain insistent that snow amounts of 15-25” are quite possible over large parts of Virginia, West Virginia, Maryland, and the District of Columbia. High-impact snows may extend further north, but the uncertainty there is greater, and the amounts should drop off rapidly toward the north edge of the storm (see embedded tweet below for one forecaster’s unofficial take). If you are in the targeted areas, now is the time to make any needed preparations. To find out the odds that a given amount of snow will fall in your area, check out the innovative probabilistic maps being generated by the NWS offices serving the Baltimore-Washington and New York City areas. We’ll be covering the storm with a WU liveblog on Friday and Saturday; watch for details.

Jeff Masters and Bob Henson

Climate Change Climate Summaries

Mid-Atlantic Braces for Potentially Epic Blizzard

By: Bob Henson , 7:53 AM GMT on January 20, 2016

For an event still several days out, computer models were in remarkable agreement late Tuesday on what could be one of the greatest snowstorms in decades for the region around Washington, D.C. It’s difficult to convey what the models are projecting without appearing to sensationalize the event, but here goes: there is every indication that snow totals on the order of two feet are quite possible across parts of the greater D.C./Baltimore area, with the potential for almost as much in Philadelphia and perhaps a foot toward New York City. Anything over 20” at Washington National Airport would be the greatest snowfall for D.C.’s official reporting station in almost a century (see below).

Although it’s too soon to get too precise about exact amounts and locations, confidence is uncommonly high for a high-impact event in the mid-Atlantic. The 0Z Wednesday run of the GFS doubled down on the prognosis, with projected snowfall amounts exceeding 30” within commuting distance of the district (see Figure 1). As a group, the ensemble members with this GFS run weren’t quite as bullish, but as noted by Capital Weather Gang, the ensemble average still projects a widespread 20” or more over much of the D.C. area. At this writing, the 0Z operational run of the ECMWF model was just coming in, and it appeared just as compelling as the GFS output below in terms of a potential record-breaking storm for the D.C. area.

Figure 1. Snowfall totals generated by the 0Z Wednesday operational run of the GFS model for the period from 0Z Wednesday (7:00 pm EST Tuesday) to 0Z Monday (7:00 pm EST Sunday). Amounts are calculated by assuming a 10:1 ratio of snow to melted water; the actual ratio can vary significantly from place to place within a storm. Keep in mind that forecasters rely on the output from a wide range of models and their trends over time before making specific snowfall predictions. Image credit: Levi Cowan,

The making of a winter blockbuster
The impetus for the storm is an upper-level impulse that was moving into the Pacific Northwest late Tuesday. The jet-stream energy will sweep across the mid-South on Thursday into Friday, helping produce a quick shot of snow and ice for parts of Arkansas, Kentucky, and Tennessee. Snow could begin as soon as midday Friday ahead of this impulse over the D.C. area. Then, as the jet-stream energy carves out a powerhouse upper low, a surface cyclone should intensify on Saturday off the Virginia coast--a prime location for big mid-Atlantic snowstorms. In classic fashion, the low-level cyclone will funnel warm, moist air from the tropical Atlantic into the region, with the air mass cooling and generating snow as it rises.

The storm’s expected evolution is “textbook,” said NOAA’s Paul Kocin in an NWS forecast discussion on Tuesday. Kocin would know: he literally wrote the book on the subject with NWS director Louis Uccellini, the classic two-volume ”Northeast Snowstorms”.

There are many failure modes for big mid-Atlantic snowstorms. For example, warm air wrapping around the surface cyclone can turn the snow to rain or sleet, or a dry slot can develop south of the surface low--and of course, the location of key features can shift. At least for the time being, the model depictions are threading the needle around these frequent storm-killers, keeping alive the possibility of a once-in-a-generation event for at least some areas. Snow could fall more or less continuously for an unusually long span of 36 hours or more, heightening the chance of big accumulations.

A serious flood threat for the mid-Atlantic coast
There is more than snow in the works with this storm. The ferocious dynamics at play during the storm’s height could produce winds of 40-50 mph or more, which would lead to blizzard conditions and huge drifts. On top of that, strong onshore winds may produce waves up to 20 feet and major coastal flooding, especially from New Jersey to the Delmarva Peninsula. The full moon on Saturday will only add to the risk of significant flood impacts. In addition, sea-surface temperatures running 5 - 7°F above average should keep the offshore surface air relatively warm, allowing strong winds aloft to mix to the surface more readily than usual for a midwinter nor’easter, as noted by the NWS/Philadelphia office in a weather discussion on Tuesday night. The risk of damaging coastal flooding will need to be watched with the same vigilance as the potential for crippling snowfall just inland.

Figure 2. D.C.'s top 1-, 2-, and 3-day winter storms, plotted by total snow amount and year. Image credit: NWS/Baltimore-Washington.

What are D.C.’s biggest storms on record?
Among the largest East Coast cities, models are suggesting that Washington has the best shot at a potential record storm. Only one storm since D.C. records began in 1884 has managed to rack up more than 20”, whereas Baltimore has had eight such storms and Dulles four. See the statistics page put together by NWS/Baltimore-Washington for more details.

Top five D.C. snowstorms over periods of up to 3 days
28” (Jan. 27-29, 1922)
20” (Feb. 12-14, 1899)
18.7” (Feb. 18-19, 1979)
17.8 (Feb. 5-6, 2010)
17.1” (Jan. 6-8, 1996)

As this storm approaches, the NWS/Baltimore-Washington office will provide experimental snowfall guidance in the form of maps and tables with detailed probabilities of exceeding various snow-amount thresholds. We can expect to see more of this type of guidance in the future; although it offers a lot of detail to parse, it provides a much richer guide to both the high- and low-end possibilities. For a reliable source of frequently updated, hyper-local coverage, you can’t beat Capital Weather Gang. Though it’s too soon to know exactly how this storm will behave, it’s not too soon to begin common-sense preparations if you’re anywhere in or near the target area.

Jeff and I will have a post Wednesday evening on the NASA/NOAA climate report for 2015, and I’ll have more on the looming East Coast storm on Thursday.

Bob Henson

Blizzard Winter Weather

Earth's 29 Billion-Dollar Weather Disasters of 2015: 4th Most on Record

By: JeffMasters, 2:43 PM GMT on January 19, 2016

Earth had a tough year for billion-dollar weather-related natural disasters in 2015, with 29--the fourth most since accurate accounting began in 1990, said insurance broker Aon Benfield in their Annual Global Climate and Catastrophe Report issued last Wednesday. The average from 2000 - 2014 was 24 billion-dollar weather disasters; the highest number since 1990 was 41, in 2013. The combined economic losses from all 300 weather and earthquake disasters in 2015 with damages of at least $50 million was $123 billion, which is 30% below the 15-year average of $175 billion. The lack of landfalling U.S. hurricanes contributed to the relatively low damage total. Natural disasters (including earthquakes) killed approximately 19,500 people in 2015, which was 75% below the 2000 - 2014 average of 79,000 fatalities. The deadliest weather disaster of 2015 was the May heat wave in India that killed an estimated 2,500 people; the costliest weather-related disaster was the $16.1 billion fires/drought in Indonesia. The U.S. had the most billion-dollar weather disasters of any country, with eleven; China came in second, with six.

By comparing the Aon Benfield numbers to historical disaster costs at EM-DAT, the International Disaster Database, we see that at least nine nations set records for their all-time most expensive weather-related disaster in 2015. For comparison, six nations had their most expensive weather-related natural disasters in history in 2013, and only one did so in 2014. Here are the nations that set records in 2015 for their most expensive weather-related natural disaster in history (with a notation for when the cost exceeded 1% of that nation's GDP):

Indonesia suffered $16.1 billion in damage from its 2015 drought and fires (1.8% of GDP.) This beats the $9.3 billion cost of the 1997 - 1998 fires for most expensive disaster in Indonesia's history.

Romania suffered $2.2 billion in damage from its drought in 2015 (1.2% of GDP.) Their previous most expensive weather-related disaster was the $1.1 billion cost (2010 dollars) of a June 21, 2010 flood.

South Africa suffered $2 billion in damage from a devastating drought in 2015. South Africa's previous most expensive disaster was the $1 billion cost (1990 dollars) of the 1990 drought.

Ethiopia suffered $1.4 billion in damage from its drought in 2015 (2.5% of GDP.) Their previous most expensive disaster was the $76 million cost (1973 dollars) of the 1973 drought.

Malawi had two weeks of heavy rain in January that triggered rampaging floods that killed at least 176 people and cost $430 million, 10% of their $4.3 billion GDP. The previous most expensive disaster in Malawi’s history was $24 million (in 1991 dollars) from the floods of March 10, 1991.

Vanuatu was struck by Category 5 Tropical Cyclone Pam on March 13, 2015, killing 16 people and doing $433 million in damage, about 53% of their $815 million GDP. The only comparable disaster in Vanuatu's history occurred in January 1985 when twin Category 3 storms--Eric and Nigel--battered the nation, doing $173 million in damage.

Chile suffered $1.5 billion in damage from flooding in late March 2015. This beat out the $1 billion price tag of their previous most expensive weather-related disaster, a cold wave in 2013.

Dominica (population 72,000) experienced a catastrophic deluge on September 27 from Tropical Storm Erika that caused $300 million in damage--57% of their GDP of $524 million. Dominica's previous most expensive disaster was the $175 million in damage from Hurricane Marilyn of 1995.

Botswana had drought that cost $44 million in 2015; the previous most expensive disaster was $5 million in flood costs from a February, 2000 flood.

U.S. sees 10 - 11 billion-dollar weather disasters
In the U.S., there were eleven billion-dollar weather disasters in 2015, according to Aon Benfield. NOAA's National Centers for Environmental Information (NCEI) gave a lower number: ten (Aon Benfeld rated the severe weather outbreak from December 23 - 26 as costing a billion dollars, while NOAA did not.) NOAA's ten billion-dollar weather disasters of 2015 marked the 4th highest yearly total for the U.S. since 1980. The ten-year average is eight. Billion-dollar events account for roughly 80% of the total U.S. losses for all weather-related disasters.

For a record eighth consecutive year, U.S. severe weather damages in 2015 topped $10 billion, according to an analysis by Munich Re, the world's largest reinsurance firm. “In no year prior to the 2008-2015 period had insured thunderstorm losses been in excess of $10 billion,” said Mark Bove, a Munich Re research meteorologist.

Figure 1. The yearly number of billion-dollar U.S. weather disasters, adjusted for inflation, as compiled by NOAA/NCEI. The yearly cost is not plotted here, though is labeled on the right side.

Figure 2. The yearly number of billion-dollar global weather disasters, adjusted for inflation, as compiled by insurance broker Aon Benfield in their Annual Global Climate and Catastrophe Reports. The increasing trend in weather disaster losses is thought to be primarily due to increases in wealth and population, and to people moving to more vulnerable areas--though the studies attempting to correct damage losses for these factors are highly uncertain. Climate change may be partly to blame for the rise in disaster losses, but we are better off looking at how the atmosphere, oceans, and glaciers are changing to find evidence that climate change is occurring--and there is plenty of evidence there. I discuss this topic in more detail in a 2012 post, Damage Losses and Climate Change.

The 29 billion-dollar weather disasters of 2015

Multi-Month Drought Disaster 1.  The El Niño event of 2015 brought devastating drought and fires to Indonesia and neighboring countries. The $16.1 billion price tag of 2015's drought and fires was 1.9% of Indonesia’s GDP, and more than twice the cost of reconstruction in Aceh after the 2004 tsunami (this cost does not include the additional damage the smoke from the fires caused to the neighboring nations of Singapore, Malaysia, and Vietnam.) In this photo, we see buildings blanketed with thick smog in Singapore on September 24, 2015. Singapore's air quality reached 'very unhealthy' levels on September 24, forcing schools to close,  as thick smog from agricultural fires in Indonesia's neighboring Sumatra Island choked the city-state. Image credit: ROSLAN RAHMAN/AFP/Getty Images.

Multi-Month Drought Disaster 2. The Western U.S. drought of 2015 brought damages estimated at $4.5 billion. According to the California Department of Water Resources, snow depths in the Sierras were the lowest on record in April, only 2% of average, and the Southern Sierras had no snow at all--nearly three months earlier than usual. California's eight largest reservoirs were 30% - 83% below their historical average in April, and the portion of the state covered by the highest level of drought--"Exceptional"--peaked at 47% during the summer of 2015. The all-time record of 58% was set during the summer of 2014. In this photo from May 24, 2015, we see houseboats moored on a shrinking arm of California's Oroville Lake reservoir, which was at 52 percent of its usual level. Image credit: MARK RALSTON/AFP/Getty Images.

Multi-Month Drought Disaster 3. It was an incredible summer for extreme heat in Europe, with Germany setting its all-time heat record (twice), and with hundreds of stations having long periods of record setting all-time heat records. Aon Benfield estimated that the heat caused 1,000 direct deaths in Europe in 2015. Extreme drought emerged in Romania, Poland, and the Czech Republic this summer during the heat wave, with a cost of at least $2.7 billion. This image shows historians recovering 17th century relics from the bed of the Vistula River in Warsaw, Poland on September 3, 2015. The water level of the Vistula, Poland's largest river, was at its lowest level since measurements began in 1789 due to the drought. The treasures being excavated were looted by an invading Swedish army in the mid-17th century and got buried in the Vistula when a Swedish barge sank. Jewish tombstones and wreckage from a WWII fighter plane were also uncovered this summer from the Vistula and its tributaries due to the low water levels. Image credit: JANEK SKARZYNSKI/AFP/Getty Images.

Multi-Month Drought Disaster 4. The most expensive natural disaster in South Africa’s history began in July, when intense drought began wreaking havoc. Some of the hardest-hit areas included KwaZulu-Natal, Mpumalanga and Limpopo provinces. Water shortages affected 2.7 million households, agricultural production plummeted, and economic damages were estimated at $2 billion. In this image, we see the carcass of a cow in the Black Umfolozi River,  in Nongoma district north west from Durban, South Africa on November 9, 2015. Image credit: MUJAHID SAFODIEN/AFP/Getty Images.

Multi-Month Drought Disaster 5. Drought in east China cost an estimated $1.8 billion in 2015. This picture taken on June 22, 2015 shows a man walking on the riverbed of a dry reservoir in Weifang, east China's Shandong province. Lack of precipitation dried up at least three big reservoirs in Weifang in 2015, affecting 440,000 people and more than 2.5 million acres of farmland, local media reported. Image credit: STR/AFP/Getty Images.

Multi-Month Drought Disaster 6. The Ethiopian National Risk Management Coordination Commission announced that it was seeking $1.4 billion to deal with 2015 drought. The United Nations called it the worst drought to affect the country in 30 years; 10 million of the country's 97 million people will need food aid in 2016, at a cost of at least $1.1 billion. This map illustrates how rainfall between March and September 2015 deviated from the 1981-2014 average across the East Africa Region. During this period, rainfall was more than 25 percent below average across large areas of central/eastern Ethiopia and eastern Sudan, and smaller areas of Djibouti, Eritrea, northeastern Somalia, northern Darfur and western Kenya. The March-September period includes the major agricultural seasons of these countries; drought at this time of year is common due to El Niño. Image credit: ReliefWeb.

Multi-Month Drought Disaster 7. Drought conditions wreaked havoc on agricultural interests in Western Canada during the summer of 2015. The province of Alberta was particularly affected, where a disaster was declared after more than 80 percent of farmers reported sustaining crop loss during the year. Damage estimates from the drought were $1 billion. In this image, we see smoke from drought-aided forest fires over British Columbia settling into valleys on July 8, 2015. Image credit: NASA.


Disaster 1. One of the most intense cold waves for so late in the year swept across the Eastern U.S. on February 16 - 22, 2015, killing eight and causing damages estimated at $3.25 billion. In this image, we see sunshine illuminating icicles in the winter-swathed landscape of Plainville, Massachusetts, on Friday, February 20, 2015. Image credit: wunderphotographer PvilleGuy.


Disaster 1. Back-to-back severe windstorms (Mike and Niklas) pounded western and central Europe from March 29 - April 1. The storms killed at least nine people and did approximately $1 billion in damage. Hurricane-force winds, including a peak gust of 192 kph (120 mph), hit parts of Germany, the UK, Netherlands, Switzerland, Austria, and Poland. In this image, we see cars covered under the part of a metal roofing in Prague on March 31, 2015, as the Czech Republic and many other parts of northern Europe were hit by extreme winds. Image credit: MICHAL CIZEK/AFP/Getty Images.

Disaster 2. Flooding hit the driest part of the world—Chile’s Atacama desert--on March 23 - 26, 2015, killing 25 people and doing $1.5 billion in damage. The largest city in the region, Antofagasta, received a deluge of 24.4 mm (0.96 inches) in 24 hours—over fourteen years of rain in one day! This remarkable video  shows incredible flooding in Chanaral, Chile, on March 25, 2015 from the deluge. In the image above, residents watch the rising flood waters of the Copiapo River, in Copiapo, Chile, Wednesday, March 25, 2015. Image credit: AP Photo/Aton Chile.


Disaster 1. The EF4 tornado that plowed across northern Illinois just west of Chicago on April 9, 2015, photographed near Stillman Valley, Illinois. The tornado was part of a four-day severe weather outbreak April 7 -10 that killed 3 people and did $1.6 billion in damage. This was the first of just three EF4 tornadoes in the U.S. in 2015; the other two EF4s occurred on December 23 in Mississippi and on December 26 in Texas. Image credit: wunderphotographer StormyPleasures (Charles Russell).

Disaster 2. A thunderstorm-generated shelf cloud near Mounds, OK, on Sunday, April 19, part of a four-day U.S. severe weather outbreak on April 18 - 21 that did $1.4 billion in damage. Image credit: wunderphotographer mrwing.


Disaster 1. A severe weather outbreak across the U.S. Plains, Midwest, and Southeast on May 6 - 13 killed 6 people and did $1 billion in damage. In this photo, we see a tornado that touched down in Cheyenne Wells, Colorado on May 9, 2015. Image credit: Wunderphotographer Guyinjeep16.

Disaster 2. A wave of severe thunderstorms, tornadoes, and torrential rains swept through the heart of the U.S. May 23 - 28, killing 32 people and causing $3.75 billion in damage. The heaviest flooding and damage was in Texas and Oklahoma, which suffered their rainiest month in recorded history. In this photo, we see a severe thunderstorm with golfball-sized hail that pounded Wetmore, KS on May 25, 2015. Image credit: Wunderphotographer idzrvit.

Disaster 3. Flooding, landslides and hail from seasonal rains in southern China from May 18 - 22 killed at least 48 people and did $1.15 billion in damage in the provincial regions of Fujian, Jiangxi, Hunan, Guangdong, Guangxi, and Guizhou. An estimated 87,000 homes were damaged or destroyed, and more than 100,000 hectares (247,000 acres) of cropland were inundated. This picture taken on May 20, 2015 shows a rescuer with a life buoy in floodwaters during an intense rainstorm that killed 7 people in Xiamen, in eastern China's Fujian province. Image credit: STR/AFP/Getty Images.


Disaster 1. Severe thunderstorms and torrential seasonal Mei-Yu rains inundated northern and southern sections of China on June 7 - 11, killing 16 people and doing at least $2 billion in damage. The provincial regions of Hunan, Guizhou, Hubei, and Gansu were the most severely impacted, with more than 20,000 homes damaged. In this picture, we see houses along a river submerged in floodwaters in Kaili in Qiandongnan, southwest China's Guizhou province on June 8, 2015. Image credit: STR/AFP/Getty Images.

Disaster 2. A severe weather outbreak from the Rockies to the Mid-Atlantic in the U.S. on June 19 - 26 killed 4 people and did $1.3 billion in damage. In this photo, we see a supercell thunderstorm that spawned a tornado near Minetare, NE on June 25, 2015. Image credit: Wunderphotographer JdyJdyJdy.


Disaster 1. Typhoon Chan-hom made landfall about 80 mi south-southeast of Shanghai, China on July 11, killing 16 people and doing at least $1.6 billion in damage. The typhoon did another $100 million in damage to Guam, Japan, Taiwan, and Korea. In this image, we see people watching huge waves from Chan-hom pounding Wenling, in east China's Zhejiang province, on July 10, 2015. Image credit:  STR/AFP/Getty Images.

Disaster 2. Heavy rainfall in China from July 20 - 24 killed 28 people and did $1.2 billion in damage. More than 238,000 residents were evacuated as floods and landslides destroyed 7,770 homes and damaged 35,100. In this picture, we see vehicles stranded on a flooded road in Wuhan, Hubei Province of China, on July 23, 2015, when 160.2 millimeters (6.31") hit the city. This was their heaviest daily rainfall since 1998, according to Changjiang Times. Image credit: ChinaFotoPress/Getty Images.


Disaster 1. Typhoon Soudelor passed directly over Saipan in the Northern Mariana Islands on August 2 as a Category 2 storm, causing widespread damage and injuring ten people on the island. Soudelor hit Japan's Ryukyu Islands on August 5, causing over $3 million in damage, then hit Taiwan as a Category 3 storm with 120 mph winds on August 7, knocking out power to 4.85 million households--the largest power outage in Taiwan's history. On August 8, Soudelor hit Fujian Province in China as a Category 1 storm with 85 mph winds, causing over $3 billion in damage. Soudelor killed a total of 41 people and did $3.2 billion in damage along its entire path. This image shows Super Typhoon Soudelor as seen by the VIIRS instrument on the Suomi spacecraft at 03:43 UTC August 4, 2015. At the time, Soudelor was a peak-strength Category 5 storm with 180 mph winds and a 900 mb central pressure.


Disaster 1. Multiple wildfires raged across California during much of September, killing seven and costing $2 billion. The Valley Fire, northwest of San Francisco, and the Butte Fire, southeast of Sacramento, were the most destructive of the fires. The Valley Fire--the third most damaging in state history, at $1.5 billion--left four people dead and destroyed 1,958 homes and other structures. The Butte Fire left two people dead and destroyed 475 homes, and was the seventh-most damaging wildfire in state history, at $450 million. The year 2015 saw the most acreage burned by wildfires in the U.S. since record keeping began in 1960, and was the costliest year in terms of money spent on firefighting efforts. In this image, we see burned out cars from the Valley Fire's rampage through Lake County, California; the fire started on September 12, 2015. Image credit: wunderphotographer noneinc.


Disaster 1. Typhoon Mujigae hit the Philippines as a tropical storm on October 2 before rapidly intensifying and striking China on October 4 as a Category 3 storm. Mujigae killed two in the Philippines and at least 20 in China. Economic losses in Philippines were estimated at $1.3 million, and were $4.2 billion in China, making Mujigae the costliest tropical cyclone of 2015. In this image, we see a rapidly intensifying Typhoon Mujigae approaching China at 0305 UTC October 3, 2015. Image credit: NASA.

Disaster 2. Torrential 1-in-1000 year rains of over two feet, associated with a plume of moisture wrapping around Hurricane Joaquin, brought tremendous flooding across much of South Carolina during the first week of October. At least 21 people were killed, and damage was estimated at $2.0 billion, including $300 million in damage to crops. In this photo, we see a church surrounded by flood waters on October 5, 2015 in Columbia, South Carolina. Image credit: Sean Rayford/Getty Images.

Disaster 3. At least 19 people were killed along the southeast coast of France by a flash flood on October 3 - 4. Cannes received a record 107 mm (4.21”) in just one hour; the previous one-hour record was 70 mm (2.76”). Damage was estimated at $1 billion. In this photo, we see a man walking past damaged cars in Mandelieu-la-Napoule, southern France, on October 5, 2015. Cars are often stacked in this manner in the aftermath of flash floods, as was the case during the catastrophic Rapid City, SD, flood of 1972 (scroll page for photo). Image credit: Anne-Christine Poujoulat/AFP/Getty Images.


Disaster 1. Five weeks of frequent torrential monsoon rainfall fed by record-warm ocean waters during November and early December inundated southern India and Sri Lanka, killing 386 people and doing $4 billion in damage. Hardest hit was Chennai, an urban area of more than 9 million people that ranks as the largest in South India and among the world’s 40 largest metro areas. Parts of Chennai spent days inundated by as much as eight feet of polluted water, with widespread power outages exacerbating the crisis. Chennai recorded 1218.6 mm (47.98”) of rain in November, the highest observed for any November in more than 100 years of record-keeping. Then, on December 1-2, a total of 345 mm (13.58”) fell in 24 hours, which smashed the city’s all-time 24-hour record rainfall of 261.6 mm on December 10, 1901. Chennai’s airport was closed for four days in early December, with some 4000 people and dozens of aircraft stranded. At one point, all runways were under water. This photo of the flooded Chennai airport is from December 2, 2015. Image credit: Atul Yadav/ Press Trust of India via AP.


Disaster 1. Windstorm Ted struck Ireland, the UK, and Norway in early December causing widespread, destructive flooding. Northwest portions of England were worst affected. Three people were killed and damage was estimated at $1.1 billion. In this image, we see residents make their way through flood waters on December 7, 2015 in Carlisle, England. Image credit: Jeff J Mitchell/Getty Images.

Disaster 2. A powerful storm system spawned a widespread outbreak of severe weather across much of the Eastern U.S. from December 22-26, killing 18 and injuring 50. Dozens of tornado touchdowns (including one EF4) were reported, along with numerous reports of damaging thunderstorm winds, baseball-sized hail and flooding. The most substantial damage was incurred in parts of Mississippi, Tennessee, Arkansas, Alabama, Illinois, Kentucky and Indiana. Total damage was estimated at $1 billion. In this image, we see an EF4 tornado near Clarksdale, Mississippi, on December 23, 2015. This tornado stayed on the ground for 73 miles and killed nine people. Image credit: Guy Malvezzi.

Disaster 3. Record atmospheric moisture over the southern U.S. during Christmas week helped fuel record rains and a deadly tornado outbreak between December 26 - 30. At least 46 people were killed by tornadoes, flooding, and associated severe weather in the outbreak, making it the U.S.'s deadliest weather event of 2015. Heavy tornado damage occurred in the Dallas, Texas region on December 26, where separate EF4 and EF3 tornadoes struck. The heavy rains brought the Mississippi River just south of St. Louis in early January to its highest level since records began in 1844, beating the great flood of 1993. Areas from the Rockies to the Northeast also incurred periods of heavy snow, freezing rain and ice. Total damage was estimated at $3 billion. In this image, we see damage from the EF4 tornado that struck Rowlett, Texas, on December 26, 2015, and killed nine people in Garland, Texas. Image credit: NWS/Fort Worth.

Disaster 4. A series of powerful Atlantic storms brought the rainiest December ever recorded in the United Kingdom, and caused significant flooding in northern sections of Britain. The hardest-hit areas included a large swath of southern Scotland, northern England, and Wales, where large areas of agricultural land and infrastructure were damaged. Damage was estimated at $2.5 billion. In this image, we see rescue teams wade through flood waters that have inundated homes in the Huntington Road area of York after the River Foss burst its banks, on Monday, December 28, 2015 in York, United Kingdom. Image credit: Jeff J. Mitchell/Getty Images.

A big thanks goes to Steve Bowen of Aon Benfield for helping out with my many questions about disaster stats. We'll be back with a report Wednesday afternoon on NOAA/NASA's global climate roundup for December 2015 and for the year as a whole, plus coverage of the potential East Coast snowstorm on Thursday/Friday. Bob Henson is at the Glen Gerberg Weather and Climate Summit in Breckenridge this week. You can follow livestreaming of weather and climate talks each morning from a group of leading meteorologists and researchers that includes Tim Brown (director of the Western Regional Climate Center), Jennifer Francis (Rutgers University), and Michael Ventrice (WSI).

Jeff Masters

Climate Summaries

Wanted: Ace Pix for International Cloud Atlas

By: Bob Henson , 3:27 PM GMT on January 18, 2016

The future of cloud classification is bright and sunny...and packed with stratus and cirrus, not to mention cirrocumulus floccus and cumulus tuba. The World Meteorological Organization (WMO) has embarked on a whole new version of its international cloud atlas, used by weather observers worldwide to ensure that clouds are described in a uniform fashion. The atlas was first published in 1939 based on work extending back to the 1800s. The most recent edition can be downloaded as a PDF, but the next version will be web-based. This opens the door for entirely new ways of presenting and documenting the world’s seemingly endless variety of clouds.

Another cool feature this time: you’ve got a chance to pitch in. The WMO launched a website in October that allows anyone to submit their photos--and videos--for consideration in the upcoming atlas. Your odds of getting imagery accepted will be highest if you go for the more obscure, harder-to-document cloud types and if you can provide details on the geographic and meteorological context of your image (see below).

Figure 1. Spectacular mamma (mammatus) clouds that formed on the back side of a severe thunderstorm that moved through the Austin, TX, area in April 2015. Although mammatus are often observed in association with tornadic supercells, they do not produce tornadoes themselves. Image credit: wunderphotographer txazgal.

An atlas for the 21st century
“Manual on the Observations of Clouds and Other Meteors” has been used for more than 80 years as the definitive reference book and guide for weather observers around the globe. (As one might guess from “meteorology,” the technical term “meteors” refers to pretty much anything found in the atmosphere.) The original 1939 atlas was split into two volumes in 1956, with Volume 1 focusing on detailed descriptions and Volume 2 on photos and brief captions. Volume 1 was updated in 1975 and Volume 2 in 1986, before the widespread availability of high-resolution digital cameras. Almost 100 of the 248 images in Volume 2 are in black and white only, so there is plenty of room to make the atlas more colorful.

Today, it’s a cinch to find web pages full of stunning cloud images and easy-to-read descriptions. However, “the classifications used in many descriptions are not accurate,” according to Steve Cohn (National Center for Atmospheric Research), who is serving as chair of the WMO committee that’s updating the cloud atlas. “There’s also a lot of really good cloud information on the web, but if you want to be sure, the International Cloud Atlas is the definitive and trusted source.”

The WMO is striving for both accuracy and accessibility in the new atlas. It’s expected to go online by 2017, when the agency's World Meteorological Day (March 23] will be centered on the theme "Understanding Clouds." Before then, said Cohn, “we’ve got an awful lot of work to do choosing photos, writing captions, and modernizing the writing style of the manual.”

Figure 2. The WMO’s Task Team on the International Cloud Atlas, pictured here, is part of the agency’s Commission for Instruments and Methods of Observations (CIMO). Left to right: Kwong Hung Tam (Hong Kong, China), Colleen Rae (South Africa), Elaine Thurig-Jenzer (Switzerland), Mike Bruhn (Australia, Vice-Chair), Marinés Campos (Argentina), Jim Trice (UK), George Anderson (UK), Steve Cohn (USA, Chair), and Ernest Lovell (Barbados).

The new web-based format will allow for major improvements to the atlas. For example:

--Time-lapse video can illustrate the evolution of cloud types

--There will be room to show how a cloud type can vary by season and/or latitude

--Radar images, thermodynamic profiles, and other tools can enhance the explanation of how various clouds form

--A revamped, user-friendly flow chart will help observers identify clouds

Figure 3. A prototype version of the updated flow chart designed to help weather observers place clouds into the 10 cloud genera (top-level categories) recognized by the WMO’s International Cloud Atlas. Along with these genera, there are 14 species (second-level categories) that describe the shape and internal structure of clouds, as well as 9 varieties (third-level categories), which deal with the transparency and arrangement of cloud elements. The WMO committee working on the atlas update has proposed adding a 15th species: volutus (Latin for “rolled”), also known as roll clouds or morning glory clouds. The atlas also recognizes several types of supplementary features and accessory clouds. Image credit: WMO.

What’s new and what’s needed from you
Working with an expert in the Latin language, the WMO committee has already come up with a few “preliminary official” names for some cloud features long recognized by weather enthusiasts. Below are a few examples of cloud features with their newly proposed Latinesque names, accompanied by images I’ve pulled from our vast WunderPhoto collection. We encourage these and other wunderphotographers to submit their work to WMO!

How to submit your image:

--Go to the Image Submission website

--Download the “Read Me First” file (PDF)

--Register yourself as a user

--When you’re ready to contribute, use the “Submit New Imagery” pull-down

The “Read Me First” file contains a great deal of helpful guidance, including a list of details required for each photo submitted (e.g., date and time of photo, latitude/longitude, direction the camera was pointing) and additional context that can improve the chance of an image being accepted (photo metadata, weather observations, etc.). There’s also a wish list of several dozen categories where WMO is in the greatest need of good imagery. Here are some categories that grabbed my eye:

Cirrus virga rainbow — virga has melted and a rainbow is visible in the water droplets

Altostratus duplicatus — two or more superposed layers, at slightly different levels, sometimes partly merged

Clouds from industry — examples are clouds of smoke and steam in industrial areas, smoke clouds created for frost protection purposes, clouds of insecticide gas or powders in agricultural areas.

Clouds from waterfalls — spray saturates air and cloud forms, usually in the form of cumulus. Brilliant rainbows often present.

“We’re already getting many photos of the more common clouds, and this is exciting,” Cohn told me. “We’ll probably have to hunt for people to contribute great images of the more unusual ones.” The team has already picked an image to illustrate asperitas (also known as asperatus), one of the most recently identified cloud features. Australian photographer Gary McArthur was named in September as the winner of a competition sponsored by the Cloud Appreciation Society in conjunction with the WMO. McArthur’s winning image was honored in an event held at the Royal Geographic Society in London.

Although the WMO website lists no firm deadline, Cohn encourages photographers and videographers to submit their work by April 2016. A poster created by Cohn and colleagues to publicize the new atlas was presented last week in New Orleans at the 96th Annual Meeting of the American Meteorological Society.

Now that our unusual midwinter burst of Northern Hemisphere hurricane activity has subsided, Jeff Masters and I will be posting later this week on some of the weather and climate highlights of 2015. In the meantime, here's a helpful explainer from WU contributor Lee Grenci on the physics behind the meteotsunami associated with powerful thunderstorms that struck the southwest Florida coast on Sunday morning. Marshall Shepherd (@DrShepherd2013) also penned an excellent recap of the event for Forbes, and WU contributor Larry Atkinson provides additional background and links.

Bob Henson

Below: Latin-derived names and descriptions for some of the cloud features and special clouds proposed to be added to the International Cloud Atlas (Note: all photos shown here are from wunderground members rather than the WMO. No official selections have yet been made in these categories.)

Figure 4. Cavum (Latin for cavity/hole/hollow) — a well-defined, generally circular (sometimes linear) hole formed in a thin layer of super-cooled cloud, which generally grows larger with time. Common names: fallstreak hole, hole-punch cloud, distrail, canal cloud. Image credit: wunderphotographer PSLTony.

Figure 5. Murus (Latin for wall) — A localized, persistent, and often abrupt lowering of cloud from the base of a cumulonimbus and from which tuba (funnel clouds) and spouts (tornadoes) sometimes form. Common name: wall cloud. Image credit: wunderphotographer wxchaser97.

Figure 6. Flammagenitus (Latin for fire + generated) — Cloud that develops as a consequence of convection initiated by heat from localized natural heat sources, such as forest fires and wild fires. Common name: pyrocumulus. Image credit: wunderphotographer FrancesJeanne.

Figure 7. Homogenitus (Latin for manmade) — Cloud that forms as a direct consequence of human activity. Common names include contrails. Image credit: wunderphotographer GVIslander.

Figure 8. Fluctus (Latin for wave/billow) — A relatively short-lived wave formation, usually on the top surface of the cloud, in the form of curls, or breaking waves. Common name: Kelvin-Helmholtz waves. Image credit: wunderphotographer Nordicmom.


Astounding Alex Hits the Azores: January’s First Atlantic Landfall in 61 Years

By: Bob Henson , 9:29 PM GMT on January 15, 2016

The unseasonable wintertime hurricane that developed over the Northeast Atlantic on Thursday has been downgraded to Post-Tropical Cyclone Alex, but its place in the annals of hurricane history is secure. Alex became a hurricane at 15Z (10 am EST) Thursday and maintained Category 1 strength for almost 24 hours. Alex’s western eyewall made landfall on the island of Terceira in the central Azores, roughly 1000 miles west of Portugal, at around 8:15 am EST with tropical-storm force winds of 60 knots (70 mph). No major damage was reported. While approaching Terceira at 7 am EST, Alex was still classified as a minimal hurricane (75 mph winds). Most of Terceira was on the west (weaker) side of Alex, so hurricane-force winds might have been observed if Alex had tracked just a bit further west. The eyewall passed over Lajes Air Force Base, producing a minimum pressure of at least 29.18” (988 mb) (no wind observations from within an hour of landfall were available). Wind gusts to 58 mph were observed at Ponta Delgada, more than 100 miles southeast of Terceira, and gusts to 55 mph were reported at Santa Maria, roughly 200 miles southeast of Terceira. At 4 pm EST Friday, Alex was located about 300 miles north of Terceira, racing northward at 40 mph with sustained winds of 60 knots (70 mph).

Figure 1. MODIS visible satellite image of Tropical Storm Alex at 9:20 am EST Friday, January 15, 2016. About an hour earlier, Alex’s western eywall passed over the Azores island of Terceira (black outline below the center of Alex). Image credit: NASA.

Not unprecedented, but very unusual
In records going back to 1851, only one other tropical cyclone in the Atlantic has made landfall in January: Hurricane Alice, which moved from northeast to southwest over the islands of Saint Martin and Saba on January 2. Alice’s heavy rain and rough seas caused damage totaling more than $4 million in current US dollars. Alice’s winds peaked at 90 mph, just above Alex’s peak sustained winds of 85 mph. The only other January hurricane in the Atlantic was Hurricane One on January 4, 1938. Three weaker cyclones have been observed in January: Tropical Storm Zeta (2005-06), Tropical Storm One (1951), and Subtropical Storm One (1978).

At any time of year, it’s quite uncommon for a hurricane to develop where Alex did. In a tweet on Thursday (see bottom), Alex Lamers noted that only one other tropical cyclone in Atlantic records is known to have become a hurricane north of 30°N and east of 30°W. That would be Hurricane Vince, one of the many oddities of the blockbuster 2005 Atlantic season. Vince went on to become the first tropical storm known to strike the Iberian Peninsula in more than 150 years.

The Northeast Atlantic is a challenging location for hurricane development thanks in large part to its relatively cool water. Alex took on its tropical characteristics while over waters that were 20-22°C (68-72°F). Although these are up to 1°C above average for this time of year, they are far cooler than usually required for tropical cyclone development. However, upper-level temperatures near Alex were unusually cold for the latitude, which meant that instability--driven by the contrast between warm, moist lower levels and cold, drier upper levels--was higher than it would otherwise be. That instability allowed showers and thunderstorms to blossom and consolidate, strengthening the warm core that made Alex a hurricane as opposed to an extratropical or subtropical storm. One could make a case that Alex was the last hurricane of 2015 rather than the first of 2016, as I discussed in a post on Thursday.

What about El Niño and climate change?
Sea-surface temperatures across the entire North Atlantic south of 35°N are warmer than average, part of a huge swath of above-average readings covering much of the globe. Some of these unusually warm waters are the result of El Niño, but the extent of the warmth--at record levels in many places--strongly suggests a link to longer-term climate change. It’s impossible to say without further research whether the extra oceanic warmth associated with Alex tipped the scales toward development, but it certainly didn’t hurt.

Alex doesn’t appear to be a classic manifestation of El Niño, based on previous January tropical cyclones since reliable El Niño records began in 1950:

Tropical Storm One (1951): La Niña
Hurricane Alice (1955): La Niña
Subtropical Storm One (1978): El Niño
Tropical Storm Zeta (2006): neutral, but leaning toward La Niña

Elsewhere in the tropics
The other hurricane shocker of this month, Hurricane Pali, has finally dissipated after toying with a run at the equator. Peaking at Category 2 strength during its eight-day life, Pali was the earliest tropical storm and earliest hurricane to develop between the International Date Line and the Americas, and it was closer to the equator than all but two other hurricanes in global records. Only two other tropical cyclones have been observed in January in the Central Pacific.

In the Southwest Pacific, a more seasonable Tropical Cyclone Victor is strengthening quickly about 300 miles east of Pago Pago. Victor could peak at Category 4 strength this weekend as it moves south, although it should not threaten any land areas.

We’ll be back with a new post on Martin Luther King, Jr., Day (Monday). Have a great weekend, everyone!

Bob Henson


Alex Becomes the Atlantic’s First January Hurricane Since 1955

By: Bob Henson , 5:19 PM GMT on January 14, 2016

History spun up over the far reaches of the Northeast Atlantic on Thursday, as Subtropical Storm Alex carved out a distinct eye within a core of intense thunderstorms, making it Hurricane Alex. The 10 am EST advisory from the National Hurricane Center put Alex’s sustained winds at 85 mph. Alex was located about 500 miles south of Faial Island in the Azores, moving north-northeast at 20 mph. A hurricane warning is in effect for the islands of Faial, Pico, Sao Jorge, Graciosa, and Terceira in the central Azores. Given the strong steering currents driving Alex, there is high confidence that at least some of the central Azores will experience tropical storm or hurricane-force wind, heavy rain, and high surf. To get a hurricane making landfall in the Azores any time of year is quite unusual (about once per 10-20 years); to get a landfall in January would be truly remarkable.

In records going back to 1851, only two hurricanes are known to have prowled the Atlantic during the month of January: an unnamed tropical storm that became Hurricane One on January 4, 1938, and Hurricane Alice, which maintained hurricane strength from December 31, 1954, to January 4, 1955. Alice topped out at 90 mph, so Alex is officially the second strongest January hurricane on record in the Atlantic. {Note: I've corrected the strength of Alice in line with its upgrade from 70 knots to 80 knots in the recently-released 1951-1955 best-track update to NOAA's HURDAT2 database. Thanks to WU contributor @philklotzbach for this catch.] Much like Alice, another tropical cyclone--Tropical Storm Zeta of 2005/06--formed in December and extended into January, and a tropical storm was recorded in early January 1951. There was also a subtropical storm in January 1978.

Figure 1. Infrared image of Hurricane Alex at 15Z (10:00 am EST) Thursday, January 14, 2016. Image credit: UW/CIMMS/SSEC.

A chilly hurricane
Designated a subtropical storm on Wednesday, Alex took on a surprisingly healthy structure overnight, with a symmetric core of showers and thunderstorms around its clear-cut eye. Sea-surface temperatures beneath Alex are only around 20-22°C (68-72°F). Although these are up to 1°C above average for this time of year, they are far cooler than usually required for tropical cyclone development. However, upper-level temperatures near Alex are unusually cold for the latitude, which means that instability--driven by the contrast between warm, moist lower levels and cold, drier upper levels--is higher than it would otherwise be. That instability allowed showers and thunderstorms to blossom and consolidate, strengthening the warm core that makes Alex a hurricane as opposed to an extratropical or subtropical storm.

Alex’s unusual life as a January hurricane will be a short one. The system is already accelerating northward ahead of a strong upper-level trough, and by late Friday it should be a powerful post-tropical low racing toward Greenland. Even though Alex will become absorbed in the higher-latitude storm system, its warm, moist air may assist in pushing temperatures over parts of Greenland more than 35°F above average this weekend into early next week.

Figure 2. WU forecast map for Hurricane Alex based on National Hurricane Center predicted positions issued at 10 am EST Thursday, January 14, 2016.

Hurricane Pali weakens to a tropical depression near equator
Late Wednesday was the first time in the modern era of tropical cyclone observing and prediction that we had simultaneous named systems in January in the Atlantic (Alex) and Central Pacific (Pali)--or, for that matter, anywhere in the Pacific. Pali is the earliest named storm and earliest hurricane on record between the International Date Line and the Americas. It reached Category 2 strength (85 knots or 100 mph) on Tuesday. While Alex was strengthening into a hurricane on Wednesday night, Pali was falling apart. By Thursday morning, Pali had decayed into Tropical Depression Pali, located at 173.0°W and just 2.5°N. Now experiencing moderate to strong wind shear, Pali should be history within the next few hours. Very few tropical cyclones have made it as close to the equator as Pali, since they normally rely on the Corilis force (which is stronger at higher latitudes) to give them a cyclonic spin. Only two other tropical cyclones have been known to make it within 2° latitude of the equator. When it formed south of 5°N latitude on January 7, Pali became the first tropical cyclone known to have existed in any of the equatorial regions used to monitor El Niño sea-surface conditions.

Which year should Alex and Pali belong to?
One might argue that Alex and Pali are actually straggler storms from the 2015 Atlantic and Central Pacific seasons, rather than the first storms of 2016. Tropical sea-surface temperatures north of the equator typically bottom out around March, so there might be some physical rationale for defining the Central/Northeast Pacific and Atlantic hurricane “years” as being from March 1 to February 28/29. In practice, though, there are very few tropical cyclones in January and February, so in most years this switch would make no difference, and it could foster public confusion. There is a much stronger physical rationale for the practice of straddling hurricane seasons across calendar years in the Southern Hemisphere, where summer arrives in late December and cyclones often form before January 1.

Hurricane Alice from 1954-55 is an interesting case in itself. It was originally recognized as a hurricane and named Alice on January 2, 1955. At that point, the same lists were being used from year to year, and there had already been a deadly Hurricane Alice in June 1954. However, post-storm analysis determined that the latter Alice had been a hurricane on December 31, 1954--which makes 1954 the Atlantic’s only year that has two hurricanes with the same name.

Bob Henson

Figure 3. Tropical Storm Pali as it was approaching hurricane strength at 2230Z (5:30 pm EST) on Monday, January 11, 2016. Image credit: NASA.


Unprecedented: Simultaneous January Named Storms in the Atlantic and Central Pacific

By: Jeff Masters , 9:46 PM GMT on January 13, 2016

As we ring in the New Year with record to near-record warm temperatures over much of Earth's oceans, we are confronted with something that would have been unimaginable a few decades ago: simultaneous January named storms in both the Atlantic and Central Pacific. The earliest named storm on record in the Central Pacific, Hurricane Pali, formed on January 7, and now the Atlantic has joined the early-season hurricane party, with Subtropical Storm Alex spinning up into history with 50 mph winds in the waters about 785 miles south-southwest of the Azores Islands. The average date of the first named storm in the Atlantic is July 9; the Central Pacific also typically sees its first named storm in July. Alex could retain its subtropical characteristics till as late as Friday, when it will be shooting northward toward Greenland en route to being absorbed in a high-latitude storm. Meanwhile, Pali is predicted to remain a tropical cyclone for at least the next five days, perhaps coming within 2° latitude of the equator--something only two other tropical cyclones in world history have been observed to do--as the storm arcs toward the southwest and eventually back northwest, potentially becoming a typhoon when it crosses the Date Line.

Figure 1. VIIRS visible satellite image of Subtropical Storm Alex on the afternoon of January 13, 2016. Image credit: NASA Worldview.

A January named storm in the Atlantic--how rare?
Alex is just the fourth Atlantic named storm to form in January since record keeping began in 1851. The others:

An unnamed 1938 hurricane became a tropical storm on January 3 well east of the Lesser Antilles Islands and lasted until January 6.

Subtropical Storm One of January 18 – 23, 1978 gained subtropical depression status over waters of about 75 °F (24 °C) about 1,700 miles east-northeast of Puerto Rico.

Tropical Storm One of 1951 was a tropical storm from January 4 - 9 in the waters a few hundred miles northeast of Puerto Rico. This was likely really a subtropical storm.

Two other named storms that formed in late December managed to last into January--Tropical Storm Zeta, which formed on December 30, 2005 and survived until January 7, 2006, west of the Cape Verde Islands, and Hurricane Alice, which formed on December 30, 1954, and tracked west-southwest into the Caribbean, where it dissipated on January 7, 1955.

Alex's genesis
Alex can trace its genesis to an area of low pressure that formed off the Southeast U.S. coast on January 7. Between January 8 and 12, pre-Alex tracked generally eastwards over ocean waters that were 22 - 25°C (72 - 77°F); these temperatures were near-record warm for this time of year (about 2 - 4°F above average). These temperatures were just high enough so that Alex was able to gradually gain a warm core and become a subtropical storm. It is unlikely that Alex would have formed if these waters had been close to normal temperatures for this time of year. The unusually warm waters for Alex were due, in part, to the high levels of global warming that brought Earth its warmest year on record in 2015. Global warming made Alex's formation much more likely to occur, and the same can be said for the formation of Hurricane Pali in the Central Pacific. To get both of these storms simultaneously in January is something that would have had a vanishingly small probability more than 30 years ago, before global warming really began to ramp up.

Figure 2. MODIS visible satellite image of Hurricane Pali taken on the afternoon of January 12, 2016. At the time, Pali was at peak strength--a Category 2 storm with 100 mph winds. Image credit: NASA.

Jeff Masters


NOAA Gins Up Major El Niño Field Campaign: Hurricane Pali Spins Southwest of Hawaii

By: Bob Henson , 2:24 PM GMT on January 12, 2016

Scientists at NOAA will be putting the well-predicted “super” El Niño of 2015-16 under a mammoth microscope over the next three months. With just enough time to line up some big observing platforms--plus a lot of other things going right--NOAA/ESRL’s Physical Sciences Division (PSD) has managed to pull together a major field effort that will analyze the mechanics of this El Niño in truly unprecedented detail.

“We’re trying to plan a field campaign in three months that would normally take two to three years,” Ryan Spackman told me in a phone chat. Spackman, an ESRL-based program manager with Science and Technology Corporation, is working with ESRL senior scientist Randy Dole to oversee the NOAA El Niño Rapid Response Field Campaign. “There are still some loose ends, but there are no show-stoppers at this point,” Spackman said. “Things are converging very quickly--which, frankly, they need to be.”

Figure 1. Sea-surface height as inferred by by NASA satellites during the current El Niño (December 27, 2015, at left, from Jason-2) and at a comparable point during the last “super” El Niño (December 28, 1997, at right, from TOPEX/Poseidon). Warmer temperatures in the upper ocean result in higher sea-surface heights, as the seawater expands. In 1997, the above-average sea surface height was generally more intense and peaked in November. In 2015, the area of high sea levels was less pronounced but considerably broader. Image credit: NASA/JPL-Caltech.

Sonde science: Gathering data on El Niño where it matters most
The crucial science question driving this field campaign is exactly how the upward-flowing energy across the El Niño region of the eastern tropical Pacific affects the surrounding atmosphere. It’s well known that the warm sea-surface temperatures (SSTs) associated with El Niño help displace showers and thunderstorms (convection) much further east than they normally roam, closer to Peru than their usual home near Indonesia. The rising motion in those storms sets off a chain of events that propagate outward for thousands of miles. Toward the top of the troposphere, or at roughly 10-15 km (6-9 miles) above the El Niño region, the updrafts of convective towers force high-altitude air to flow outward, just as it would from a hurricane.

“It’s that diverging air that has an impact on the subtropical jet, extending it and enhancing it,” said Spackman. In turn, the strengthened subtropical jet has impacts on weather downstream at mid-latitudes, including enhanced winter rainfall from California all the way to Florida. “We can draw these links, but we don’t have many observations from the El Niño region, and our weather prediction models don’t include all the underlying physics they need to model that process,” Spackman said. Not surprisingly, a number of studies have pointed to the El Niño region as being a key source of larger-scale model uncertainty during El Niño episodes.

To get a handle on what’s going on this winter, a vast number of atmospheric profiles--potentially more than 1000, which is a hefty number indeed for such a project--will be collected in two ways:
--radiosondes (balloon-borne instrument packages launched from ship or shore)
--dropsondes (parachute-borne instrument packages deposited from aircraft)

Radiosondes have been a mainstay of routine weather observing since the 1930s. Despite the immense value of satellites, there is still no substitute for the data that a radiosonde or dropsonde can gather. Wind data, in particular, are often difficult for satellites to obtain with precision, especially in the presence of multiple cloud layers. The sonde-derived profiles this winter will be collected over a domain spanning thousands of miles, but the focal point, as one might expect, is the area of unusual oceanic warmth now being produced by El Niño over the central and eastern tropical Pacific.

Figure 2. Left: NOAA’s Gulfstream-IV jet has flown on hurricane and winter-storm reconnaissance missions since 1996. Image credit: NOAA. Right: A view of NASA's Global Hawk unmanned aircraft from one of its wings. Image credit: NASA.

Two aircraft, a ship, and an island
The first platform for the project is NOAA’s Gulfstream-IV hurricane-hunter aircraft (see Figure 2 above). The high-flying Gulfstream-IV is typically used to monitor the atmosphere around hurricanes, so it’s an ideal tool for sampling how the El Niño convection is affecting the surrounding air at high altitudes. Up to 20 G-IV missions will be conducted between January 19 and March 3 from a home base at Honolulu International Airport, with as many as 30 dropsondes to be deployed per mission. “We’ll be transiting quite a bit to get to the intertropical convergence zone near the equator,” says Spackman. “Probably half of each flight will be just getting there.”

The Niño3.4 region is the “meat of where we’re going to operate--nominally from the dateline to about 130°W.  It’s going to be a stretch to get very far to the west and the east, so we expect a couple of deployments out of Tahiti or perhaps American Samoa.” This will allow for a broader study area, including the Niño4 region further west, where this year’s El Niño has been particularly strong. Along with the dropsondes, the G-IV’s tail-mounted Doppler radar will be invaluable for gathering wind data, said Spackman.

Figure 3. Areas of the equatorial Pacific that are monitored to produce weekly, monthly, and seasonal estimates of the evolution of El Niño and its counterpart, La Niña. Variations in the Niño3.4 sea surface temperature (center) are the most common index of El Niño strength. Image credit: NOAA/NCEI.

The relatively quiet Atlantic hurricane season of 2015 turned out to be a boon for El Niño research, as it left open many potential flight hours for a second platform (see Figure 2 above): NASA’s Global Hawk unmanned aerial system (UAS), based at NASA Armstrong Flight Research Center (Edwards Air Force Base, California). The El Niño sampling will piggyback onto the Global Hawk’s previously planned missions for an activity called SHOUT: Sensing Hazards with Operational Unmanned Technology. The idea behind SHOUT is to gather focused data from mid-latitude and subtropical regions identified as crucial to an unfolding weather scenario (e.g., a developing storm far out in the Pacific) in order to improve forecasts over the United States several days later. “We’re hoping we can devise flight strategies where we coordinate the G-IV flights at lower latitudes with what SHOUT is doing at higher latitudes,” Spackman said.

The El Niño project will be able to draw on as many as six 24-hour flights during three weeks in February. Each flight will carry and deploy up to 75 dropsondes, with the flights operated remotely from NASA/Armstrong and the sondes launched with a system developed at the National Center for Atmospheric Research.

Figure 4. NOAA Ship Ronald H. Brown, a research vessel named in honor of the late U.S. Secretary of Commerce, has been carrying out missions around the world since 1997. Here, two workers from the Ron Brown examine a buoy in the Tropical Atmosphere Ocean (TAO) array (left). Image credit: NOAA, courtesy Oak Ridge National Laboratory.

Another platform--NOAA’s Ronald H. Brown research vessel (Figure 4, above) is part of the project thanks to another happy coincidence. The Ron Brown was already scheduled to be plying the eastern tropical Pacific from mid-February to mid-March to carry out maintenance on the dozens of buoys that monitor the atmosphere and ocean across the region (among other things, helping to detect El Niño itself). For the new field project, two PSD staff will launch 6 to 8 radiosondes each day, around the clock, from aboard the ship as it hops from buoy to buoy along a zigzagging path from Hawaii to California.

There’s also Kiritimati (also known as Christmas Island), one of the Line Islands. Routine radiosonde launches from this remote site were discontinued years ago, but it’s in a prime location for this project: at 2°N, due south of Hawaii and near the heart of the sea-surface warming of El Niño. Two radiosondes a day will be launched from the island from January 23 to March 28.

Figure 5. A view of Kiritimati from the International Space Station. The world’s largest coral atoll by land area, Kiritimati covers about 150 square miles, with a population of around 5,000. Image credit: NASA/Wikimedia Commons.

Along with the four platforms above, a 3-centimeter-wavelength radar will be deployed in the south San Francisco Bay area. It will help fill a gap in the existing national network of Doppler radars, thus leading to more accurate rainfall estimates for the central California coast.

As it compiles an irreplaceable trove of data for research, ESRL will also feed many of those observations into the network of real-time data used by numerical forecast models around the world. The enhanced data will thus help improve the day-to-day forecasts produced this winter by NOAA, ECMWF, and other leading centers (although the Global Hawk data are not yet certified for operational use by NOAA). "In many ways, this is a ripe playground for the SHOUT program," Spackman said. ”Their goal is to demonstrate that targeted observations have an impact on select high-impact forecast metrics such as precipitation."

Figure 6. A cross section of the dominant circulation cells affecting the Northern Hemisphere, going from north to south as you move from left to right. The showers and thunderstorms (convection) depicted at right shift from the western Pacific closer to the Americas during El Niño, which alters the downstream effects on the subtropical jet stream. Image credit: CMMAP/Colorado State University.

More on the project from Randy Dole
I asked ESRL’s Randy Dole to weigh in on how ESRL was able to pull together such an ambitious field project on short notice, and what the effort might tell us about how El Niño works.

BH: How exactly do the warm equatorial SSTs associated with El Niño act to strengthen the subtropical jet?  Is it simply due to a strengthening of the Hadley circulation, or are there additional processes going on as well? 

RD: “There are multiple factors, but you've got the primary one. Tropical convection usually focuses near the warmest waters, which are shifted eastward in El Niño years. Poleward flow diverging from near the top of the convection turns eastward when viewed in the earth's frame of reference (i.e.,through the Coriolis force). Eastward turning occurs in both hemispheres, so unusually strong subtropical westerly jet streams occur in both Northern and Southern hemispheres related to El Niño. Because El Niño-related convective enhancement occurs mainly in the central to eastern tropical Pacific, the jet strengthening is typically seen over the central and eastern subtropical Pacific.”

BH: How does this year’s campaign compare to what happened during the last “super” El Niño?

RD: ”In 1997-98 there was no rapid rapid response field campaign over the tropical Pacific, although one might have been possible. To be sure, there were flights for the NORPEX field campaign, but these were primarily conducted to perform targeted observations in the extratropical northeast North Pacific aiming at improving short-term forecasts. Spinning up a rapid response field campaign, as opposed to tweaking a campaign that was already planned, requires many factors, including the ability to anticipate such an event and its potential impacts. Typically, planning and developing logistical support for a campaign of the scale we plan to conduct takes 2-3 years, rather than a few months. So it's a daunting challenge, and hard to know whether those around in 1998 even conceived such a thing. Since 1998 the NASA Global Hawk has become available, so that adds to a capability that would not have existed in 1998. But in the end, in addition to an event driver, it takes many factors to come together: the will, hard work, and support from leadership to shift out of business-as-usual, the default option. The closest analogy we could come up with in NOAA was the agency's Deepwater Horizon response, but that was in reaction to a disaster, rather than being proactive, as we are trying to be here.”

Figure 7. The domain for the NOAA El Niño Rapid Response Field Campaign atop a map of recent sea-surface temperatures (redder colors indicate warmer temperatures relative to the seasonal average). Image credit: NOAA/ESRL.

BH: What's an example of a burning-curiosity question for you that you hope can be answered through these various observations?

RD: ”First, I would like to resolve how well our current weather and climate models do in representing the tropical atmospheric response to a major El Niño. In the absence of direct observations, it's difficult to be sure. My strong suspicion is that the models have major errors and, if so, those errors will be apparent in our observations. As this is the first link in the chain from El Niño to West Coast rainfall, knowing how well our models simulate this link is critical.

“Second, if there are significant tropical errors, how important are they for NOAA forecasts, and over what time scale? The observations may not answer that question directly, but they will point us in the direction of what we will need to do to find out, and what the implications will be for NOAA's future observing and forecast modeling systems. The challenges are common to weather and climate models, as tropical errors will influence everything from short-term predictions to longer-term climate change projections.

“Third, at heart I simply want to understand how the system works. Roughly, from an atmospheric perspective we might consider that El Niño as turning up a "knob" on ocean conditions, and when the knob is turned to very high heavy winter rainfall is much more likely in California.  But what are the most important factors determining this relationship?  It's easy to conjecture, but I would like to see these observations bring us closer to providing definitive answers. In the long run that will help us identify what will be needed to improve predictions of variables that matter to the public and decision-makers.”

Organizers of the NOAA El Niño Rapid Response Field Campaign will provide an overview of the field campaign and related partnerships at this week’s 96th Annual Meeting of the American Meteorological Society in New Orleans (7:00 - 8:30 pm Tuesday, room 243 of the Ernest N. Morial Convention Center). You can follow news about the project at the dedicated ESRL website.

Figure 8. Infrared satellite image of Hurricane Pali as of 1330Z (8:30 am EST) Tuesday, January 12, 2015. Image credit: NOAA/NESDIS.

Figure 9. MODIS visible satellite image of Hurricane Pali taken at 5:30 pm EST January 11, 2016. At the time, Pali was intensifying into a Category 1 storm with 85 mph winds. Image credit: NASA.

Strange times in the tropics: Hurricane Pali in the Central Pacific; possible subtropical storm in the North Atlantic
It’s not entirely out of the question that a tropical cyclone will be churning over or just west of the Central Pacific the field campaign kicks off next week. Late Monday night, Hurricane Pali became the earliest hurricane on record for both the Central and Northeast Pacific (the region between the International Date Line and the Americas), beating 1992’s Ekeka, which became a hurricane on January 30. Still packing winds of 85 mph early Tuesday morning, Pali was located unusually close to the equator--at 7.5°N, 171.6°W, or about 1300 miles southwest of Honolulu--and was moving south-southeast at about 7 mph. Pali should continue drifting equatorward over the next several days, gradually bending toward the west and potentially back toward the west-northwest if it hangs on. Sea-surface temperatures are more than warm enough to support Pali along its projected track, at 28-29°C (82-84°F). However, moderate wind shear (10 - 20 knots) could keep Pali from strengthening, and there are few historical precedents for tropical cyclones at such low latitudes. In its 4:00 am EST update, the Central Pacific Hurricane Center noted: “It is fair to say the uncertainty is higher than normal as Pali moves closer to the equator.” Wunderblogger Lee Grenci has a Tuesday morning post analyzing the possibility that Pali could cross the equator--something no tropical cyclone has ever been observed to do.

Meanwhile, a tenacious extratropical storm over the Central North Atlantic still has a chance to take on subtropical characteristics later this week as it angles southeast, east of 40°W longitude. The National Hurricane Center gives this system a 40% chance of development through Sunday. Sea-surface temperatures are on the cool side for a fully tropical system, though.

Bob Henson

El Niño Hurricane

Army Corps Opens Bonnet Carré Spillway; a January Subtropical Storm in the Atlantic?

By: Jeff Masters and Bob Henson , 11:54 PM GMT on January 10, 2016

At 10 am CST January 10, 2016, the U.S. Army Corps of Engineers opened the gates on the Bonnet Carré Spillway in St. Charles Parish, Louisiana to allow flood waters from the swollen Mississippi River to flow into Lake Pontchartrain. This is the earliest that the Corps has been forced to open the spillway, and just the 11th time since it became operational in 1931 that it has been used. The only other time the spillway has been opened in January was back in 1937. All of the other openings have come in spring or early summer. Opening of the spillway is expected to keep the Mississippi River below its 17-foot flood stage in New Orleans--just 3 feet below the tops of the levees. The river is expected to crest in New Orleans on Tuesday, January 12. There is also chance that the Corps will be forced to open the Morganza Floodway in Pointe Coupee Parish northwest of Baton Rouge, which would divert water from the Mississippi River down the Atchafalaya River. This floodway has been opened only twice--in 1973 and 2011--and has a considerably higher cost of being opened than opening of the Bonnet Carré Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Floodway. The Sunday morning forecast from the NWS River Forecast Center predicted that the Mississippi River would crest at Red River Landing, just above the Morganza Floodway, on January 18. The predicted crest of 61.0' is just 2.4' below the all-time record crest of 63.39' set on May 18, 2011, when the Corps was forced to open the Morganza Floodway in order to relieve pressure on the Old River Control Structure. The earliest the Corps would open the Morganza Floodway would be Wednesday, January 13.

Figure 1. Hundreds of people, some parking a mile or more away, trekked to the Bonnet Carré Spillway to view its historic opening on January 10, 2016. Image credit: Bob Henson.

An eyewitness account from Bob Henson on the opening of the Bonnet Carré Spillway
My fellow blogger Bob Henson happened to be in the New Orleans area on Sunday, ahead of this week's annual meeting of the American Meteorological Society. He provided this first-hand report: "Chilly north winds were whisking across the bayou as hundreds of people streamed toward the Bonnet Carré Spillway. I was glad I brought a heavy coat from Colorado! The best viewing was on the outlet side. After a press conference with several speakers, including New Orleans mayor Mitch Landrieu, U.S. Corps of Engineers workers began the laborious process of using cranes to carefully pull the long wooden pins, called needles, upward from the control structure, one by one. About 8,000 cubic feet of water per second was already forcing its way through the crevices between needles. As each needle was removed, more water cascaded from the Mississippi into the outlet flowing toward Lake Pontchartrain. It was fascinating to watch the whole process unfold at its own deliberate pace, and to hear the gradually increasing roar of the water. I also loved the slice of Louisiana life carved out in this very public event. Despite all the horrors of Katrina, and what one person characterized as a ‘love-hate relationship’ with the Corps of Engineers, the mood here was very upbeat. This time, the system was working as it was meant to. Even the winter chill added a touch of novelty, as it underscored the unusual timing of this massive flood crest. I’m feeling incredibly lucky that the timing coincided so well with my arrival here for this week's American Meteorological Society (AMS) Annual Meeting--which seems to be so often cursed with bad weather, but not with historic high water!"

Figure 2. The opening of the Bonnet Carré Spillway was a spectacle in itself. Crowds watched as wooden pins called needles guarding the Bonnet Carré Spillway were methodically removed.Image credit: Bob Henson.

Figure 3. Extracting a needle--very carefully--from the Bonnet Carré Spillway. Each of the 350 concrete bays holds 20 needles. Image credit: Bob Henson.

Figure 4. Crowds lined the slopes of the outlet between the Mississippi and Lake Ponchartrain. Image credit: Bob Henson.

Figure 5. On the Mississippi side of the Bonnet Carré spillway. Is this Louisiana or Minnesota?!

Video 1.  Two work crews remove pins from two bays of the Bonnet Carré Spillway.

Video 2.  Comments from New Orleans native Lisa Arcoleo.

Video 3.  Comments from Sabina Miller (@sweetsabinas), Thibodaux, LA.

January subtropical storm possible in the Atlantic late this week
In the Atlantic, a powerful nontropical low is stirring up the waters east of Bermuda with a large area of strong winds, some as high as 75 mph (Category 1 hurricane-force!) Models continue to move this system toward the southeast and then east this week, which could put it in a more favorable environment for subtropical development. Ocean temperatures are at near-record warm levels for this time of year in the waters east of Bermuda (about 3 - 4°F above average), which is just high enough so that a pre-existing storm like this one, which has been cut off from the jet stream and lingers over these marginally warm waters for a few days, has the potential to become a subtropical storm. On Sunday afternoon, the National Hurricane Center gave 2-day and 5-day odds of this system developing into a subtropical storm of 20% and 40%, respectively. Regardless of development, the storm may bring heavy rains and strong winds in excess of 50 mph to the Azores Islands on Friday.

Figure 6. MODIS satellite image of the low pressure system east of Bermuda that was generating hurricane-force winds on the afternoon of January 10, 2016. Image credit: NASA Worldview.

A January named storm in the Atlantic--how rare?
Only one January tropical storm has formed in the Atlantic since record keeping began in 1851--an unnamed 1938 hurricane that became a tropical storm on January 3 well east of the Lesser Antilles Islands and lasted until January 6. There has also been one subtropical storm to form in January: Subtropical Storm One of January 18 – 23, 1978. Two other named storms that formed in late December managed to last into January, though--Tropical Storm Zeta, which formed on December 30, 2005 and survived until January 7, 2006, west of the Cape Verde Islands, and Hurricane Alice, which formed on December 30, 1954, and tracked west-southwest into the Caribbean, where it dissipated on January 7, 1955.

Figure 7. VIIRS visible satellite image of Tropical Cyclone Ula taken on January 10, 2016. At the time, Ula was a Category 4 storm with 130 mph winds. Image credit: NASA Worldview.

Ula becomes Earth's first Category 4 storm of 2016
Tropical Cyclone Ula became Earth first Category 4 storm of 2016 on Sunday, hitting sustained wind of 130 mph in the South Pacific waters about 300 miles east-northeast of New Caledonia. Ula is headed poleward on a track which should miss any populated islands, fortunately. Ula passed near Vanuatu's southern islands after hitting Fiji and Tonga last week. Ula was at Category 2 strength when it hit Tonga, causing widespread damage, with roofs ripped from homes and utility lines downed by strong winds. No deaths or injuries have been reported from the storm, though.

The Southern Hemisphere’s annual tropical cyclone season, which peaks in February - March, has gotten off to an unusually slow start. Ula reached hurricane strength on December 31, becoming the latest-forming first hurricane-strength tropical cyclone of a Southern Hemisphere tropical cyclone season since the 1987-1988 season, according to CSU’s Dr. Phil Klotzbach.

Tropical Storm Pali meandering in Central Pacific
The earliest tropical storm on record in the Central Pacific, Tropical Storm Pali, had 50 mph winds on Sunday evening as it meandered over the waters about 1,450 miles southwest of Honolulu, Hawaii. Pali is not a threat to any land areas.

We'll have a new post by Tuesday morning.

Jeff Masters and Bob Henson

Flood Hurricane

Warm, Wet Year for U.S.; Record Heat in South Africa; Tropical Storm Pali Intensifies

By: Bob Henson , 5:56 PM GMT on January 08, 2016

Many Americans were throwing on T-shirts or rain gear instead of heavy coats last month, in what proved to be the nation’s mildest and wettest December in more than a century of record-keeping. On Thursday, NOAA’s National Centers for Environmental Information (NCEI) released initial data on December and for the year 2015. (A full report will be issued on January 13). As a whole, 2015 came in as the second warmest and second wettest year on record for the contiguous U.S.

It’s hard to overstate the striking character of December’s mildness. Millions of people along the Eastern Seaboard experienced it first hand, as all of the big cities (and many smaller ones) from Washington, D.C., to Portland, Maine, smashed their previous records for December warmth. New York City’s Central Park went through the entire month of December without dipping down to freezing, whereas all prior Decembers back to 1871 had reached 32°F at least six times. As shown in Figure 1, each state east of the Mississippi--plus Minnesota, Iowa, and Missouri--saw its warmest December on record, and even the coolest states were close to their long-term December average. All told, close to 12,000 daily records (warm highs and warm lows) were set across the nation in December, as noted by There was plenty of moisture to be had as well: 40 states came in above average on precipitation, with Iowa and Wisconsin getting their wettest December on record and Minnesota, Missouri and Illinois coming in at second-wettest. These rains contributed to the exceptional flood crest now moving along the lower Mississippi River.

Figure 1. Temperature and precipitation rankings by state for December 2015. Higher numbers indicate warmer and wetter conditions. States labeled 121 (dark red and dark green) experienced the warmest or wettest Decembers in 121 years of national recordkeeping. Image credit: NOAA/NCEI.

For the year as a whole, the warmth and moisture were widely distributed across the contiguous U.S. There were more than twice as many daily record highs as record lows for the year, but as noted by Climate Central, a brutally cold February over the eastern U.S. was the main factor keeping 2015 from being the nation’s warmest year. The northwest and southeast corners of the 48 states, Washington and Florida, both had their warmest year on record, as did Oregon and Montana. All 48 contiguous states saw at least a top-25 warmest year. Only five were notably drier than average in 2015--California, Montana, Connecticut, Rhode Island, and Massachusetts--while many central states had a top-10 wettest year, with Texas and Oklahoma notching their wettest on record. (During the first week of 2016, moisture has also returned to California in a big way, thanks to a parade of soggy Pacific storm systems; more on that in a future post.)

Figure 2. Temperature and precipitation rankings by state, as in Figure 1, but for the entire year of 2015 (January – December). Higher numbers indicate warmer and wetter conditions. States labeled 121 (dark red and dark green) experienced the warmest or wettest year in 121 years of national recordkeeping. Image credit: NOAA/NCEI.

How did the U.S. stay so mild and moist at the same time?
The combination of unusual warmth and unusual moisture is a standout in itself. Heavy, persistent precipitation often means lots of sun-blocking clouds that cut down on heating. Very warm months are typically the driest ones. That was the case in June 1933 and May 1934, two Dust Bowl months that still reign as the warmest and driest May and June in U.S. history (thanks to Nick Wiltgen at for this find). What made the difference last month, and last year, was the record-warm sea surface temperatures over the tropical Pacific and Atlantic, a function of El Niño and other short-term oceanic patterns as well as long-term warming related to human-produced climate change. These warm SSTs allowed vast amounts of moisture to evaporate into air masses flowing toward the lower 48 states. In turn, this led to countless records for precipitable water (the amount of water vapor in the air above a given measuring site). Near the surface, the moisture helped to keep nighttime temperatures consistently high in many locations.

Here’s just one example: During the nine-day period from December 23 to 31, the lowest temperature observed in Key West, Florida, was 78°F. This happens to be the previous record-warm minimum for the entire month of December, going back to 1871! This is the first time I’ve heard of any U.S. location with more than a century of weather-observing history that managed to tie or set a monthly record on so many consecutive days. Key West’s daily lows were an astounding 79°F on December 25, 27, 28, 29, and 31. Finally, on January 3, the mercury dropped below 69°F, for the first time since April 1--making it the longest such streak at or above 69°F (277 days) in Key West history.

Figure 3. Average temperatures for the period September-December since 1895 for the contiguous U.S. This past Sep-Dec was more than 1°F warmer than the previous record-holder, 1998. Image credit: NOAA/NCEI.

The big wet
Two states saw their wettest months on record in May 2015: Texas (8.81”) and Oklahoma (14.40”). South Carolina didn’t manage that feat during its extreme October deluge, but the state did end up with its wettest autumn on record (23.62”, more than 5” above the previous record). Hand in hand with these large-scale dousings, there were some particularly hefty year-long accumulations at individual sites, including these wettest local years on record:

St. Louis, MO: 61.24” (old record 57.96” in 2008)
Fort Smith, AR: 73.93” (old record 71.81” in 1945)
Dallas-Fort Worth, TX: 61.61” (old record 53.54” in 1991)

Figure 4. A Japanese camellia (japonica) in bloom at Danville, Virginia, on December 25, 2015. Image credit: wunderphotographer WeatherWise.

A Christmas warm wave for the ages
December culminated in a memorable week-plus period of record warmth that swaddled most of the nation east of the Rockies. On Christmas Eve and Christmas Day, a total of 847 U.S. stations tied or broke record daily highs, according to preliminary data on NOAA’s U.S. Records website. Dozens of those previous marks were bested by at least 10°F. In Hanover, New Hampshire, it was 67°F on Christmas Day--a full 17°F warmer than any other Christmas in 122 years of recordkeeping. Just after noon on Christmas Eve, the heat index in Virginia Beach, VA, reached an absurdly unseasonable 86°F! Not to be outdone, the northwestern Alaska town of Kotzebue basked in the relative warmth of 37°F--tying its record monthly high--on the evening of December 30.

Chilly weather has returned to much of the central and eastern U.S. for early January. Although the cold is a bracing experience for those who got accustomed to extreme autumn mildness, it’s merely garden-variety chill by climatological standards. We are unlikely to see many record lows or record-cold highs in the foreseeable future, whereas a day of near-record warmth is once again possible in the mid-Atlantic and southern New England on Sunday. Still, one of the coldest pro football games in recent decades is on tap for Sunday, when the Minnesota Vikings will host the Seattle Seahawks in a wild-card playoff. Though probably well above record levels, temperatures at the 12:05 pm kickoff at the non-domed TCF Bank Stadium in Minneapolis are expected to be near or just below 0°F, with a wind chill as cold as –20°F possible. According to the Weather Channel’s Michael Butler, the Seahawks have never played in temperatures any colder than 16°F (Dec. 3, 2006, in Denver). The Vikings, who are temporarily based at TCF Bank Stadium while awaiting a new roofed stadium, have kicked off only once before in subzero weather: on Dec. 3, 1972, with a temperature of -2°F.

All-time record heat in southern Africa
A heat wave in the midst of an already scorching summer has baked southern Africa this week, producing the hottest readings ever observed in a number of locations. According to weather records researcher Maximiliano Herrera, Botswana set the world’s first all-time national high temperature of 2016 on Wednesday, January 6, then exceeded it on Thursday, January 7, as the city of Maun hit at least 43.8°C or 110.8°F (officially rounded upward to 44°C). Herrera, one of the world's top climatologists, maintains a comprehensive list of extreme temperature records for every nation in the world on his website, which lists dozens of all-time local record highs set since the first of this year across South Africa, Botswana, and Zimbabwe. South Africa’s capital city, Pretoria, soared to 42.7°C (108.9°F) on Thursday--the most recent in a string of several all-time record highs there over the last few weeks. In the nation’s largest city, Johannesburg, an all-time record of 36.5°C set only last November has been topped several times, most recently on Thursday with a high of 38.9°C (102.0°F). The heat across South Africa has also toppled many all-time world temperature records for any location at altitudes between 1000 and 1600 meters (3280 - 5250 feet), according to Herrera.

A severe multi-year drought in and near South Africa has drained reservoirs, devastated farming, and parched the landscape, allowing the summer sun to heat the land and air more efficiently (the same process that fostered record heat in California over the last several years). Making things worse, El Niño tends to produce drier-than-average conditions over southern Africa. Record-warm temperatures over the Indian Ocean are also playing a role, according to researchers. “The warming of the Indian Ocean is contributing to the stable air mass over the interior,” said Mary Scholes (University of the Witwatersrand) in an email. As global temperatures continue to climb this century due to human-produced greenhouse gases, Africa is expected to warm more quickly than the global average. Particularly high warming rates are expected over southwestern South Africa, Botswana, and Namibia, according to the chapter on Africa (PDF) in the 2014 Fifth Assessment Report (Working Group II) of the Intergovernmental Panel on Climate Change (IPCC). “Africa as a whole is one of the most vulnerable continents [to climate change] due to its high exposure and low adaptive capacity,” notes the report.

Figure 6. Infrared image of Tropical Storm Pali at 17Z (12 pm EST) Friday, January 8, 2015. Image credit: NOAA/NESDIS.

Tropical Storm Pali gathers strength in Central Pacific
The tropical depression located about 1400 miles southwest of Hawaii became Tropical Storm Pali on Thursday. Pali is the earliest tropical storm on record to develop between the International Date Line and the Americas (though one could argue the record-smashing 2015 tropical season in the Central Pacific has sloshed into 2016). As of 15Z (10 am EST) Friday, January 8, Pali’s top sustained winds had reached 55 knots (65 mph). Pali is embedded in a low-level trough between a westerly wind burst south of the equator and strong trade winds north of the storm, with easterly wind shear evident in satellite imagery. Pali’s northwestward motion is expected to slow to a crawl this weekend, after which the storm may bend back toward the south. The strong vertical wind shear (20 - 30 knots) and interactions with the surface trough are expected to gradually weaken Pali over the next several days.

In the Northwest Atlantic, a powerful nontropical low is stirring up the ocean west of Bermuda with a large area of strong winds, some as high as 65 mph. Models continue to move this system toward the east and southeast by early next week, which could put it in a more favorable environment for subtropical development. On Friday morning, the National Hurricane Center gave this system a 30% chance of subtropical or tropical development over the next five days.

Have a great weekend, everyone!

Bob Henson

Climate Summaries Climate Change Hurricane Extreme Weather

Rare January Depression in Central Pacific; Atlantic Subtropical Storm Next Week?

By: Bob Henson , 5:10 PM GMT on January 07, 2016

After a record-smashing hurricane season in 2015, the Central Pacific is off to a record-early start with Tropical Depression One-C, which formed on Thursday morning in the waters about 1,500 miles southwest of Honolulu, Hawaii. According to NHC hurricane specialist Eric Blake, TD 1-C's genesis date of January 7 breaks by six days the record for earliest formation of a tropical cyclone in the Central Pacific set by Tropical Storm Winona on January 13, 1989. TD 1-C was able to form because of an unusual wind pattern near the equator associated with El Niño--a burst of westerly winds near the equator, when combined with a more typical east-to-west flow of trade winds farther to the north helped create an area of counter-clockwise spin. A sprawling region of showers and thunderstorms associated with TD 1-C at roughly 4°N and 171°W is located squarely atop some of the warmest waters associated with the powerful El Niño event now under way--29.5°C (85°F). Weak steering currents make it difficult to judge TD-1C's future path, although a slow motion northwestwards appears likely over the next couple of days.

The GFS and ECMWF models support the idea of TD 1-C attaining tropical storm strength between now and Saturday, January 9. If so, it will be named Tropical Storm Pali. Only two tropical storms have been recorded in January across the Central and Northeast Pacific (the region north of the equator and east of the International Date Line) since reliable records began in 1949. The first one was 1989’s Winona, which attained tropical storm strength on January 13 and peaked with sustained winds of 55 knots. In 1992, Ekeka was christened as a tropical storm on January 28 well west of Hawaii before becoming a rare February hurricane, with Category 3 winds reaching 115 mph.

Figure 1. Latest satellite image of Invest TD 1-C.

A spin that crossed the equator
Remarkably, TD 1-C appears to have roots on the other side of the equator! Last week, a short-lived tropical depression (TD 9-C) originated as the northern member of a pair of twin cyclones. Such sets of twins usually straddle the equatorial Pacific, with the northern member rotating counterclockwise and the southern member clockwise. In between, these circulations produce a zone of low-level westerly winds that can act to reinforce or intensify El Niño conditions across the equatorial Pacific. Last week’s twin cyclones were displaced so far south that the northern member (eventually to become TD 9-C) was located just south of the equator, close to the International Date Line, with a powerful westerly wind burst in between the cyclones. On the south side of this wind burst, Severe Tropical Cyclone Ula has been threading its way around several Southwest Pacific islands since becoming a depression on December 29 and strengthening to a Category 3 cyclone by January 1. The Joint Typhoon Warning Center projects that Ula will continue its winding path well south of Fiji over the next few days, remaining at weak to middling tropical-storm strength

An animated visible satellite loop created by Dan Lindsey (CIRA/Colorado State University), using data from the Himiwari-8 satellite, clearly shows the counterclockwise rotation as the northern cyclone approached the equator on December 28. Drifting northward, it gained enough strength to be christened TD 9-C late on December 30. Located at 2.8°N, it was the lowest-latitude system on record to become a tropical cyclone in the Western Hemisphere, according to Michael Lowry (The Weather Channel). TD 9-C’s circulation dissipated late on January 1, but the large field of moisture associated with it remained, providing fertile ground for the development of TD 1-C this week.

Figure 2. Left: Streamers reveal the twin circulations along and south of the equator near the International Date Line on December 27, 2015, with a large area of strong westerly winds in between. Right: Infrared satellite imagery shows the large field of moisture associated with the northern circulation, which went on to become Tropical Depression 9. Image credit: (left) courtesy Mark Lander, University of Guam.

Tropical cyclones developing near the equator are very rare, since the Coriolis force (a function of Earth’s spin) does not force areas of low pressure to rotate in either direction at 0° latitude. But tropical cyclones near the equator are not unprecedented. In 2004, the center of low pressure that eventually became Severe Cyclonic Storm Agni in the Northwest Pacific briefly moved south of the equator. Agni became a depression at 1.5°N, tying with Tropical Storm Vamei (2001) as having the most equatorward development of any tropical cyclone on record. The recent strong westerly wind burst between the Pacific’s twin cyclones no doubt helped give TD 9-C some of the spin that it would have otherwise been unable to gain due to its equatorial location.

Elsewhere in the tropics (January edition)
Unusual activity has been percolating in the Atlantic as well. On Tuesday, Brazil’s Navy Hydrographic Center identified a subtropical depression east of Rio de Janeiro. It was briefly classified as a tropical depression on Wednesday, although both designations had been removed in the center's 12Z analysis on Thursday morning. It was once thought that tropical cyclones never formed in the South Atlantic, but Category 1 Hurricane Catarina shocked Brazil--and the world of tropical meteorology--when it crashed into the coast of Brazil’s Santa Catarina province on March 27, 2004, causing more than $300 million in damage. Forecasters are now tracking down subtropical systems in the South Atlantic about once per year, on average, though tropical storms (those with fairly symmetric warm cores) are much less common. Jon Erdman and Chris Dolce have more background on this South Atlantic event in a Wednesday article at

There is also potential for a large and powerful January cyclone to evolve over the North Atlantic subtropics between Bermuda and the Azores Islands early next week, as consistently predicted by the GFS and ECMWF models. This cyclone is now several hundred miles northeast of the Bahamas, strengthening as an non-tropical system ahead of a subtropical jet stream typical of El Niño winters. A strong upper-level ridge will develop to the north of the cyclone as it races east and then southeast. Phase-space diagrams from Florida State University show this system taking on subtropical characteristics (asymmetric warm core) this weekend and early next week. Upper-level winds will remain strong in the vicinity of this system, and ocean temperatures will be a marginal 24-25°C (75-77°F), suggesting that any potential development would be subtropical rather than tropical. If this storm were to get a name, it would be "Alex." The Atlantic’s most recent tropical cyclone during January was Tropical Storm Zeta, which served as the closing act of the blockbuster 2005 hurricane season. Zeta formed on December 30 and survived until January 7, 2006, west of the Cape Verde Islands.

Bob Henson

Figure 3. A classic comma-shaped extratropical cyclone, located northeast of the Bahamas at 1630Z (11:30 am EST) on Thursday, January 7, 2016, has some potential for subtropical development as it moves into the central Atlantic early next week. Image credit: NASA Earth Science Office and NOAA.

Portlight's Paul Timmons to serve as Red Cross Disability Integration Coordinator
The disaster relief charity, founded and staffed by members of the wunderground community, has received some well-earned recognition from the Red Cross, which announced on Dec. 16 that Paul Timmons of Portlight Strategies will serve as disability integration coordinator for the national provider of emergency assistance and disaster relief. Portlight Strategies, based in Charleston, S.C., is the only known national and international disaster relief agency that focuses on serving people with disabilities.

“I’m super excited that Paul has agreed to do this because I think that he’s got a tremendous amount of credibility with the disability community and I think he speaks disaster,” said Brad Kieserman, vice president of Red Cross Disaster Operations and Logistics, in an interview with

Timmons will be responsible for building disability infrastructure within the Red Cross, including building relationships, improving service delivery and implementing disability specific training. “Kieserman’s embracing of our interests and his embracing of the Red Cross getting our issues right has just been a game changer,” Timmons said. “It’s allowed us to get the conversation out of the American Red Cross headquarters and out into the field where it should be.“

According to Timmons, fixing the divide between the Red Cross and the disability community will require constant community organizing. “We can’t train our way out of this,” he said. “We can’t meet our way out of this. We can’t conference call our way out of this. We have to organize our way out of this.” He encourages the disability community to stay involved in the process.

Because of serious issues such as Red Cross shelters not being accessible, there is tension between the Red Cross and the disability community admits Kieserman, but he’s optimistic the situation can be fixed. “I hope that going into the new year with Paul and Portlight now under contract with the Red Cross, and with the Red Cross committing to increased emphasis and focus on disability integration issues, we will have the opportunity to turn the corner,” he said.

You can check out Portlight's latest activities and donate to Portlight's disaster relief fund at the website.

Jeff Masters


Earth's Top Ten Weather/Climate Events of 2015

By: Jeff Masters , 3:00 AM GMT on January 05, 2016

1) Earth's Warmest Year on Record
The final numbers are not in yet, but 2015 is virtually certain to beat 2014's record as the planet's warmest year since record keeping began in 1880. Nine of the first eleven months of 2015 set new all-time monthly records for global heat in the NOAA database, and the two most recent months that have been catalogued--October and November 2015--had by far the warmest departures from average of any months on record. The new record was caused by the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, combined with a extra bump in temperature due to the strongest El Niño event ever recorded in the Eastern Pacific. Record warm ocean temperatures in the tropics in 2015 led to a global coral bleaching event, which is expected to cause a loss of 10 - 20% of all coral worldwide. The lingering warmth from El Niño makes 2016 a good bet to exceed even 2015's warmth.

Figure 1. Departure of the global surface temperature from average for the period January - November, for all years from 1880 to 2015. The year 2015 will easily beat 2014 as the warmest year on record. Image credit: NOAA.

2) Earth's Strongest El Niño Event on Record
A potent El Niño event in the Eastern Pacific that crossed the threshold into the "strong" category in early July peaked in mid-November with the highest weekly heat ever observed in the equatorial Eastern Pacific waters. Sea-surface temperatures (SSTs) in the Pacific’s Niño3.4 region, between 90°W and 160°E longitude and 5° north/south latitude, are considered the benchmark for rating the strength of an El Niño event. The weekly departure of SST from average in this region hit +3.1°C (5.6°F), NOAA announced in their November 23 El Niño update. This exceeds the previous 1-week record warmth in the equatorial Pacific of 2.8°C above average set during the week of November 26, 1997; accurate El Niño records extend back to 1950. The standard measure for the strength of an El Niño event is the three-month average Niño 3.4 departure of SST from average, and the El Niño of 2015 is tied with 1997 for the strongest on record. The October-November-December three-month average Niño 3.4 SSTs were 2.3°C above average in both 2015 and 1997. The 2015 record-strength El Nino was helped along in mid-March 2015 by the strongest Madden Julian Oscillation (MJO) event ever recorded (the MJO is a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days.) The Wheeler-Hendon MJO index hit 4.67 on March 16, 2015, beating the old record of 4.01 set on February 14, 1985. MJO record keeping began in 1974 (with no data available from 3/17/1978-12/31/1978 due to satellite problems). Thanks go to CSU's Phil Klotzbach for stats on the MJO record.

Figure 2. Sea-surface temperatures (SSTs) in the Pacific’s Niño3.4 region, between 90°W and 160°E longitude and 5° north/south latitude, are considered the benchmark for rating the strength of an El Niño event. The weekly departure of SST from average in this region hit +3.1°C (5.6°F) in mid-November 2015, beating the previous record of +2.8°C set during November 1997 during that year's super-El Niño. Image credit: Jan Null Golden Gate Weather, via Twitter.

3) Earth's Strongest Western Hemisphere Hurricane Ever Measured: Hurricane Patricia
Record-warm ocean waters helped Hurricane Patricia explode into a Category 5 storm with 200 mph sustained surface winds and a central pressure of 879 mb off the Pacific coast of Mexico on October 23, 2015, making Patricia the most intense hurricane ever observed in the Western Hemisphere (the Eastern Hemisphere has had several more intense typhoons, however, with Super Typhoon Tip of 1979 holding the all-time record with an 870 mb central pressure.) Patricia made landfall in an relatively unpopulated area near Cuixmala in Southwest Mexico on October 23 as a Category 5 storm with 165 mph winds, killing fourteen and doing $300 million in damage. Patricia helped bring the Accumulated Cyclone Energy (ACE) in the Northeast Pacific (east of the Date Line) to its second highest value on record, just behind 1992 (288 in 2015 vs. 292 in 1992). The Northeast Pacific (east of the Date Line) also had more major hurricanes (11) than any other year on record, breaking the old record of 10 set in 1992. Thanks go to Dr. Phil Klotzbach of Colorado State University for these last two stats.

Figure 3. Hurricane Patricia as seen by the MODIS instrument on NASA's Terra spacecraft at 1:30 pm EDT October 23, 2015. At the time, Patricia was the most intense hurricane ever observed in the Western Hemisphere, with 200 mph sustained surface winds and a central pressure of 879 mb. Image credit: NASA.

4) Indonesia's $16 Billion Fires: Most Expensive Disaster of 2015
Earth's most expensive weather-related disaster of 2015--and the most expensive disaster in Indonesia's history--is still underway in that nation, where massive clouds of smoke from agricultural fires have choked the lungs of tens of millions of people for months. The World Bank estimated the smoke will cost $16.1 billion in agriculture production, forest degradation, health, transportation and tourism. The disaster may also be the deadliest disaster of 2015, depending upon how one treats the difficult task of determining air pollution deaths. Over 10,000 adults are likely to die from pollution from the fires, judging by the results of a 2013 study in Nature Climate Change by Marlier et al., El Niño and health risks from landscape fire emissions in Southeast Asia. Thanks go to Steve Bowen of insurance broker Aon Benfield for the World Bank damage estimate.

Figure 4. Buildings (background) along Shenton way business district are blanketed with thick smog in Singapore on September 24, 2015. Singapore's air quality reached 'very unhealthy' levels on September 24, forcing schools to close, as thick smog from agricultural fires in Indonesia's neighboring Sumatra Island choked the city-state. Image credit: ROSLAN RAHMAN/AFP/Getty Images.

5) Deadliest Weather Disasters of 2015: Heat Waves in Indian, Pakistan, and Europe
Earth's hottest year in recorded history brought three significant heat waves responsible for thousands of deaths. The worst was India's horrid May heat wave, which killed 2,500--the second deadliest in India's recorded history, and the fifth deadliest in world history. According to statistics from EM-DAT, the International Disaster Database, India's only deadlier heat wave was in 1998, when 2,541 died. A separate heat wave in June 2015 in Pakistan killed 1,229, ranking as the world's eighth deadliest heat wave in recorded history. Record summer heat in Europe killed hundreds more. Note, though, that death tolls from heat waves are very difficult to estimate, since excess heat is typically not listed as the primary cause of death in cases where the victim has a pre-existing condition such as heart or lung disease. Below is the list of top ten deadliest heat waves in world history as compiled by EM-DAT, the International Disaster Database, which uses direct deaths for their statistics, and not excess mortality. Included in bold are two heat waves in 2015.

The 10 Deadliest Heat Waves in World History
1) Europe, 2003: 71,310
2) Russia, 2010: 55,736
3) Europe, 2006: 3,418
4) India, 1998: 2,541
5) India, 2015: 2,500
6) U.S. and Canada, 1936: 1,693
7) U.S., 1980: 1,260
8) Pakistan, 2015: 1,229
9) India, 2003: 1,210
10) India, 2002: 1,030

Figure 5. A young Indian child pours water on himself as he tries to cool himself off in New Delhi on May 28, 2015. Image credit: MONEY SHARMA/AFP/Getty Images.

6) Deadliest Storm of 2015: Floods in South India and Sri Lanka Kill 328
Five weeks of frequent torrential monsoon rainfall fed by record-warm ocean waters during November and early December inundated southern India and Sri Lanka. The resulting floods killed 328 people and did at least $3 billion in damage. Hardest hit was Chennai, an urban area of more than 9 million people that ranks as the largest in South India and among the world’s 40 largest metro areas. Parts of Chennai spent days inundated by as much as eight feet of polluted water, with widespread power outages exacerbating the crisis. Chennai recorded 1218.6 mm (47.98”) of rain in November, the highest observed for any November in more than 100 years of record-keeping. Then, on December 1-2, a total of 345 mm (13.58”) fell in 24 hours, which smashed the city’s all-time 24-hour record rainfall of 261.6 mm on December 10, 1901. Chennai’s airport was closed for four days in early December, with some 4000 people and dozens of aircraft stranded. At one point, all runways were under water.

Figure 6. India's flooded Chennai airport on Thursday, December 2, 2015. Image credit: Atul Yadav/ Press Trust of India via AP.

7) Wild Christmas Week Flooding and Storms in the U.S.
Record atmospheric moisture over the southern U.S. during Christmas week helped fuel record rains and two deadly tornado outbreaks between December 23 - 28. At least 59 people were killed by tornadoes, flooding, and associated severe weather in the outbreak, making it our nation's deadliest weather event of 2015. The heavy rains brought the Mississippi River just south of St. Louis in early January to its highest level since records began in 1844, beating the great flood of 1993. We expect record floods in the spring from the combined effect of snow melt and heavy rains, but to get one in the winter when the moisture-carrying capacity of the atmosphere is usually at a minimum and there is no contribution to the flood from snow melt is off-the-charts freakish. During the insane rains that deluged the Mississippi Valley during the week of Christmas, record levels of atmospheric moisture were observed. This moisture largely came from the southern Gulf of Mexico, where ocean temperatures were at record or near-record warm levels for so late in the year. These waters would not have been so warm without global warming helping make 2015 the warmest year on record globally.

Figure 7. Damage from the tornado that struck Rowlett, Texas, on Saturday evening, December 26, 2015. The tornado was rated EF4, and killed eight people in Garland, Texas. Image credit: NWS/Fort Worth.

8) Tropical Cyclone Pam
A tropical cyclone catastrophe of nearly unprecedented dimensions affected the unlucky South Pacific island nation of Vanuatu, after a Friday the 13th strike in March by Category 5 Tropical Cyclone Pam. At its peak, Pam's 165 mph winds made it one of only ten Category 5 storms ever rated by the Joint Typhoon Warning Center (JTWC) in the waters east of Australia. The official tropical cyclone warning center for the area, the Fiji Meteorological Service, estimated that Pam's central pressure bottomed out at 896 mb, making it the second most intense tropical cyclone in the South Pacific basin after Cyclone Zoe of 2002. Pam was at its peak strength, with 165-mph Category 5 winds, when it passed over several small Vanuatu Islands to the north of Efate Island, Vanuatu's most populous island (population 66,000.) Pam is one of only two Category 5 cyclones in recorded history to make landfall on a populated island in the waters east of Australia. The only other Category 5 landfall event among the nine other Category 5 storms to affect these waters since 1970 was by the strongest tropical cyclone on record in the basin, Cyclone Zoe of 2002. Pam killed 16 people and did $433 million in damage, making it by far the costliest disaster in Vanuatu's history. According to EM-DAT, the international disaster database, the only comparable disaster in Vanuatu's history occurred in January 1985 when twin Category 3 storms--Eric and Nigel--battered the nation, affecting 118,000 people and doing $173 million in damage.

Figure 8. Tropical Cyclone Pam approaching Vanuatu's capital city of Port Vila on Efate Island, as seen by the MODIS instrument on the Aqua satellite at 10:20 pm EDT March 12, 2015. At the time, Pam was a Category 5 storm with 160 mph winds. Image credit: NASA.

9) Hurricane Joaquin
Hurricane Joaquin was the strongest Atlantic hurricane since 2007, topping out just below Category 5 strength on October 3 with 155 mph winds. Joaquin was the second deadliest and second most damaging Atlantic named storm of 2015, causing $100 million in damage in the Central Bahamas, where it lingered for several days. Joaquin's death toll was 35, with 33 of these deaths occurring from the sinking of the ill-fated cargo ship El Faro. Although Joaquin tracked far to the east of the United States, a non-tropical low over the Southeast tapped into the hurricane's moisture, causing record-shattering rains and flooding across North and South Carolina. Several areas of South Carolina saw accumulations exceeding the threshold for a 1-in-1,000-year event. The subsequent floods inundated large areas of the state, killing 21 people and causing over $2 billion in damage.

Figure 9. Hurricane Joaquin as seen by the GOES-East satellite at 7:45 am EDT October 1, 2015. At the time, Joaquin was an intensifying Category 2 storm with 110 mph winds. The last position of the cargo ship El Faro, in the northwestern eyewall of Joaquin, is shown. Image credit: United States Navy and NOAA.

10) Record Central Pacific Hurricane Activity
Record warm ocean temperatures and record low wind shear in the Central Pacific (140-180°W) helped fuel a wildly active hurricane season. A few of the notable records set, courtesy of Dr. Phil Klotzbach of Colorado State University:

- 8 named storms formed in the North Central Pacific, shattering the old record of 4 named storms set in 1982
- 14 named storms, 8 hurricanes and 5 major hurricanes either formed or tracked into the North Central Pacific from the Northeast Pacific in 2015. This broke the old records of 10 named storms (set in 1982 and 1997), 5 hurricanes (set in 1982 and 1994) and 3 major hurricanes (set in 1994).
- 127 Accumulated Cyclone Energy (ACE) units were generated in the North Central Pacific, breaking old ACE record of 107 set in 1994.
- Record high SSTs and record low wind shear (since ~1980) were recorded when averaged from July-October across the North Central Pacific Main Development Region (7.5-20°N, 180- 140°W)

Figure 10. A mosaic of infrared satellite images from geostationary satellites showing all 15 tropical storms to reach or form in the Central Pacific basin in 2015. The images were obtained through the Naval Research Lab's Online archive. Miraculously, the Hawaiian Islands (outlined in aqua) seemed to have a zone of exclusion around them, and all the storms missed the islands. In 2014, Tropical Storm Iselle hit the Big Island and two other hurricanes came within 200 miles of the islands, and the busy Hawaiian hurricane season of 2014 was linked to climate change in a 2015 Bulletin of the American Meteorological Society annual attribution report on how extreme events may be influenced by climate change. Image credit: Kevin Kodama/National Weather Service Honolulu Office. H/T to, where I originally saw this image posted.

The next post will be Thursday afternoon, when stats from NOAA summarizing the 2015 weather year in the U.S. will be available.

Jeff Masters (with Bob Henson helping out on the India floods section)

Climate Summaries

Historic Mississippi River Flood Brings Highest Crest on Record Below St. Louis

By: Jeff Masters , 12:54 AM GMT on January 04, 2016

A historic and unseasonable flood has brought the highest flood levels ever recorded to the Mississippi River south of St. Louis, thanks to more than 10 inches of rain that fell over a three-day period that began Christmas Day. At least 25 deaths in Illinois and Missouri are being blamed on the flooding. The Mississippi River crested at its third highest water level on record in St.Louis on January 1. On January 2, the southward-propagating crest brought the second highest flood on record to Chester and the highest flood on record to Cape Girardeau and Thebes. On Monday, January 4, the crest is expected to be about 200 miles south of St. Louis at Caruthersville, Missouri, bringing the third highest flood ever observed there. The latest flood forecasts for the Mississippi River issued Sunday evening by NWS River Forecast Center predicted no other locations would see an all-time record crest, with crests between the 2nd and 10th highest on record expected along most of the Lower Mississippi and the lower portions of two main tributaries, the Ohio and Arkansas Rivers.

Figure 1. Precipitation over much of the drainage basin of the Mississippi River in Wisconsin, Iowa, Illinois, Missouri, and portions of surrounding states during December 2015 averaged 200 - 600% of normal (dark blue to purple colors.) Image credit: NOAA/NWS/AHPS.

Figure 2. The Mississippi River downstream of St. Louis at Thebes crested on January 2 at the highest level ever observed. Flood records at this location extend back to 1844. The sudden dips in the water levels may be due to levee breaches. Image credit: NOAA/AHPS.

Huge stresses being put on Mississippi River levees
The record flood is putting record stresses on portions of the Mississippi River levee system. According to the Associated Press (AP), the Len Small Mississippi River levee near Miller City, IL--just north of the river's confluence with the Ohio River at Cairo, Illinois--was breached Saturday, bringing the total number of levee breaches from the flood to eleven. The area affected was mostly agricultural, but about 500 people living behind the levee in the towns of Olive Branch, Hodges Park, and Unity were told to move to higher ground. The Len Small levee is a local flood control district levee that fronts the Mississippi River, and is not a U.S. Army Corps of Engineers levee.

Video 1. Aerial view of the Len Small levee break in southern Illinois on January 2, 2016. Thanks go to wunderground member beell for posting this video in my blog comments.

Andy Revkin's December 30 Dot Earth blog in the New York Times quoted Nicholas Pinter, a professor of applied geology at the University of California, Davis, who has extensively studied flood risks on the Mississippi River. Pinter was an author of a 2011 paper showing areas where surface erosion, compaction of soil or subsidence lowered levee elevations in ways that raise risks in such floods. Here’s his quote:

"The big big issue for the next couple of days is levee performance, as flood levels exceed 1993 in some locations. The current forecasts call for large levee systems like Grand Tower and Degognia and others…to be at overtopping levels. Most of the Middle Mississippi River levees are currently rated Unacceptable (like 44.5% of rated levee miles nationwide); plus there are major geotechnical issue documented by our research--subsidence and compaction and un-permitted levee modifications using road gravel that is unsuited to flood control. There is room for optimism--this flood wave is very sharp and will be days long…rather than weeks. My personal fear is that many of these levees are degraded in ways that may rear up suddenly as near-record flood levels roll through. I am very apprehensive for neighbors and colleagues and friends on the bottoms."

Figure 3. Changes in levee elevation as calculated between 1998 - 2007 along the Mississippi River near its confluence with the Ohio River near Cairo, Illinois. Red indicates places where levees along the Mississippi River have subsided in ways that increase flood risks. The maximum sinking measured was 4.1 feet. Image credit: Nicholas Pinter and Southern Illinois University.

Army Corps may be forced to open two flood structures
On January 12, the flood crest is expected to arrive in New Orleans, bringing the Mississippi River to its 17-foot flood stage in the city--just 3 feet below the tops of the levees. In past years, though, when the river has been forecast to rise to 17 feet in the city, the Army Corps of Engineers has opened up the Bonnet Carré Spillway in St. Charles Parish, which diverts water into Lake Pontchartrain and keeps the river from reaching flood stage in New Orleans. According to a December 30 news story in The Advocate, the Army Corps will make a decision by January 9 on whether or not to open the Bonnet Carré Spillway. The last time the spillway was opened in January was back in 1937, its first year of operation. There is a lower chance that the Corps will be forced to open the Morganza Floodway in Pointe Coupee Parish between New Orleans and Baton Rouge, which would divert water down the Atchafalaya River. Opening this spillway has a considerably higher cost than opening the Bonnet Carre Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Floodway. The Corps also has the option of increasing the flow of Mississippi River water into the Atchafalaya at the Old River Control Structure in Concordia Parish. Operating the Old River Control Structure in this way, though, puts stress on the structure, as I explained in my 2011 blog post, America's Achilles' heel: the Mississippi River's Old River Control Structure. The Sunday evening forecast from the NWS River Forecast Center predicted that the Mississippi River would crest at Red River Landing, where the Old River Control Structure is located, on January 18. The predicted crest of 62.5' is just 0.9' below the all-time record crest of 63.39' set on May 18, 2011, when the Corps was forced to open the Morganza Floodway in order to relieve pressure on the Old River Control Structure.

Another huge concern is what shape the levees will be in after this record January flood subsides. After the great 2011 flood, about a billion dollars was required to bring the levee system back to the state it was in before is was damaged by the flood. The Army Corps will not have much time to do repairs before the annual spring flood arrives in May on the Mississippi, so the levee system will be much more vulnerable than usual to major flooding. So far, though, the odds of major spring flooding along the Mississippi appear to be below average. The winter snow pack in the Dakotas, Minnesota, and Wisconsin is much below average, thanks to a warm December. The water content of the snow pack on January 3, 2016 was about 20% of what was present on January 3, 2011, in advance of the great 2011 spring flood. In addition, we may be helped out by the fact that El Niño tends to cause lower-than-average precipitation over the key Mississippi drainage area of the Midwest.  See the NWS outlooks (scroll down pages to get to the precip maps) at:

I'll have a new post on Tuesday, when my top-ten list of 2015 weather events is scheduled to go up.

Jeff Masters


Earth's Nine Category Five Storms of 2015: 2nd Most on Record

By: Jeff Masters , 3:21 AM GMT on January 01, 2016

Category Five: the phase evokes an almost reverential awe in novice and seasoned hurricane watchers alike, as one considers the incredible power and majesty of these most perfect but terrifyingly destructive storms on the planet. As we look back on the year in weather, a striking feature of 2015 is the bumper crop of these fearsome storms that appeared--thanks to El Niño bringing record-warm ocean temperatures to large swaths of the Pacific Ocean. Nine Category 5 storms whipped into life over the world's oceans in 2015: five in the Northwest Pacific, one in the Northeast Pacific, one in the Southeast Pacific, and two in the South Indian Ocean. Since accurate global satellite records began in 1990, only one year has seen more. That record is held by the El Niño year of 1997, which had twelve Category 5 storms--ten of them in the Northwest Pacific. Two other season have seen nine Cat 5s--2004 and 2014. Earth averaged just 4.6 Category 5 storms per year between 1990 - 2014, according to ratings made by NOAA's National Hurricane Center and the U.S. Navy's Joint Typhoon Warning Center. The majority of these storms occur during the July - November peak of the Northern Hemisphere's tropical cyclone season, with 59% of all Cat 5s occurring in the Northwest Pacific.

Figure 1. Global Category 5 tropical cyclones from 1990 - 2015, as rated by NOAA's National Hurricane Center and the U.S. Navy's Joint Typhoon Warning Center. There is no obvious trend in the numbers, though the past two years have seen an unusually large number of Cat 5s.

Here, then, is a "rogue's gallery" of all the Category 5 storms on Earth in 2015:

Cat Five #9, Northeast Pacific. Hurricane Patricia as seen by the MODIS instrument on NASA's Terra spacecraft at 1:30 pm EDT October 23, 2015. At the time, Patricia was the most intense hurricane ever observed in the Western Hemisphere, with 200 mph sustained surface winds and a central pressure of 879 mb. Patricia made landfall in an relatively unpopulated area near Cuixmala in Southwest Mexico on October 23 as a Category 5 storm with 165 mph winds, killing fourteen and doing $300 million in damage. Image credit: NASA.

Cat Five #8, Northwest Pacific. Super Typhoon Atsani as seen by the MODIS instrument on NASA's Aqua spacecraft at 05:30 UTC August 19, 2015. Six hours later, Atsani hit peak strength with 160 mph winds and a 925 mb central pressure. Atsani spent its life over the open ocean waters to the east and southeast of Japan, and did not affect any land areas. Image credit: NASA.

Cat Five #7, Northwest Pacific. Super Typhoon Soudelor as seen by the VIIRS instrument on the Suomi spacecraft at 03:43 UTC August 4, 2015. At the time, Soudelor was a peak-strength Category 5 storm with 180 mph winds and a 900 mb central pressure. Soudelor passed directly over Saipan in the Northern Mariana Islands on August 2 as a Category 2 storm, causing widespread damage and injuring ten people on the island. Soudelor hit Japan's Ryukyu Islands on August 5, causing over $3 million in damage, then hit Taiwan as a Category 3 storm with 120 mph winds on August 7, knocking out power to 4.85 million households--the largest power outage in Taiwan's history. On August 8, Soudelor hit Fujian Province in China as a Category 1 storm with 85 mph winds, causing over $3 billion in damage. Soudelor killed a total of 41 people and did $3.2 billion in damage along its entire path. Image credit: NASA Suomi NPP Satellite Twitter feed.

Cat Five #6, Northwest Pacific. Super Typhoon Dolphin as seen at 01:05 UTC May 16, 2015 by the MODIS instrument. At the time, Dolphin was an intensifying Category 4 storm and would reach peak intensity as a Category 5 storm with 160 mph winds 17 hours later. Dolphin affected Guam and Rota in the U.S. Mariana Islands as a Category 2 storm with sustained winds of 110 mph. The eye of Dolphin passed through the channel between the islands of Guam and Rota, and Andersen Air Force Base on Guam experienced sustained winds as high as 84 mph and a peak gust of 106 mph. Damage in the Mariana Islands from the typhoon was estimated at $10 million. Image credit: NASA.

Cat Five #5, Northwest Pacific. Super Typhoon Noul as seen by the new Japanese Himawari-8 satellite at 00:50 UTC May 10, 2015. At the time, Noul was a peak-strength Category 5 storm with 160 mph winds and a 915 mb central pressure. Noul hit northeast Luzon in the Philippines at 09 UTC May 10 as a Category 5 storm with 160 mph winds, killing two and causing less than $1 million in damage. Noul was the fourth strongest typhoon on record for so early in the year. The only stronger ones were Super Typhoon Amy of 1971, which deepened to 890 mb on May 2, Super Typhoon Iris of 1951, which hit 909 mb on May 3, and Super Typhoon Maysak that occurred just over a month previously (March 31, 2015, 905 mb central pressure.) Image credit: The University of Wisconsin/CIMSS, which put together a remarkable hi-res satellite animation of the storm from the Himawari-8 satellite (which is still in check-out mode.)

Cat Five #4, Northwest Pacific. Super Typhoon Maysak as seen from the International Space Station at approximately 6 pm EDT Tuesday March 31, 2015 (just after dawn local time.) At the time, Mayask was at peak intensity, with sustained winds of 160 mph (as estimated by the Joint Typhoon Warning Center) and a central pressure of 905 mb (as estimated by the Japan Meteorological Agency.) Maysak was the strongest typhoon ever observed in the Northwest Pacific prior to April, and one of only three Category 5 typhoons ever observed in the Northwest Pacific so early in the year. Maysak killed 9 and did $8.5 million in damage to several small islands in the Federated States of Micronesia, which it struck at Category 5 strength on March 31. The nine people killed by the storm made it Micronesia's second deadliest storm in recorded history, according to EM-DAT. Their deadliest disaster was Category 4 Typhoon Chataan, which dumped 19.90" (506 mm) of rain in 24 hours on Chuuk, causing landslides that killed 47 people. Maysak is the 2nd most expensive disaster in Micronesia's history; the most expensive was Category 1 Typhoon Nina, which did $6 million (1987 dollars) in damage on November 21, 1987.

Cat Five #3, Southeast Pacific. Tropical Cyclone Pam near peak intensity (165 mph winds, 896 mb pressure), as seen by the VIIRS instrument on the Suomi satellite at 10:42 am EDT March 13, 2015, just southeast of Efate Island, where the capital of Vanuatu, Port Vila, lies. Pam killed 16 people and did $250 million in damage to the island nation of Vanuatu, making it the 2nd most expensive disaster in their history (the most expensive, according to EM-DAT: Cyclone Eric of 1985, which did $173 million in damage in 1985 dollars, or $377 million 2015 dollars.) Pam was the third most intense storm in the entire Southern Hemisphere by central pressure, only after Cyclone Zoe of 2002 and Cyclone Gafilo of 2004. Pam is tied with Cyclone Orson and Cyclone Monica for having the strongest sustained 10-minute average winds of any cyclone on record in the Southern Hemisphere. Image credit: @NOAASatellites.

Cat Five #2, Southwest Indian. Tropical Cyclone Eunice as seen by the MODIS instrument at 05:30 UTC January 30, 2015, when the storm was at peak intensity (160 mph winds, 900 mb pressure.) Eunice was the 3rd strongest cyclone ever observed in the Southwest Indian Ocean by pressure, and the strongest by winds. Fortunately, Eunice affected only ocean areas in the South Indian Ocean.

Cat Five #1, Southwest Indian. Tropical Cyclone Bansi as seen from the International Space Station, when lightning was lighting up the eye. The date of the photo was not given, but presumably was January 13, 2015, when Bansi was near peak intensity as a Category 5 storm with 160 mph winds, according to the Joint Typhoon Warning Center. Bansi grazed the French island of La Reunion, off the coast of Madagascar, on January 13, dumping up to 22 inches of rain. After weakening to a Category 2 storm, Bansi passed about 90 miles from Rodrigues Island, which recorded sustained winds of 93 mph. Approximately 90 percent of the island was left without power. Image credit: Astronaut Sam Cristoforetti.

The near misses
Three tropical cyclone achieved an intensity of 155 mph winds, just missing the cutoff for being classified as Category 5 storms. It is possible that in post-season analysis, these storms will be classified as Category 5 (this happened to two typhoons in the Pacific in post-season analysis after the 2014 typhoon season.) The near-miss storms of 2015 were Hurricane Joaquin in the Atlantic, Tropical Cyclone Chapala in the Arabian Sea, and Super Typhoon Nangka in the Northwest Pacific.

Happy New Year, everyone! I'll be back with a new post on the first Monday of 2016.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Category 6™


Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather