Category 6™

First tornado death of 2013 ends record 219-day streak without a tornado death

By: JeffMasters, 7:50 PM GMT on January 30, 2013

A powerful tornado ripped through Adairsville, Georgia, northwest of Atlanta, at 11:19 am EST this morning, killing at least one person in a mobile home park. The tornado caused major structural damage in the downtown district, and overturned approximately 100 cars on I-75 near Exit 306 (see eyewitness video here, with swear words.) Eight injuries, some serious, are also being reported from a tornado just southeast of Calhoun, GA around 11:30am EST. NOAA's Storm Prediction Center has placed most of the Southeast in their "Slight Risk" region for severe weather for Wednesday, a step down from the "Moderate Risk" potential issued on Tuesday for the Midwest. Three other tornadoes have hit Georgia today, and there were 79 reports of wind damage due to high winds as of 2 pm EST along the cold front that triggered today's severe weather, from Alabama to Pennsylvania. Tornado watches continue for a wide swath of the Southeast this afternoon, from Alabama to North Carolina.


Figure 1. Car overturned by the tornado near Adairsville, Georgia, on January 30, 2013. Image courtesy of WSB-TV on http://pic.twitter.com/2lAL0Lmc.



Figure 2. Radar reflectivity (top) and Doppler velocity (bottom) images of the tornado that hit Adairsville, Georgia at 11:19 am EST Wednesday, January 30, 2013. Adairsville is under the circle with a "+" in it.


Figure 3. A wild weather day in the Southeast: NOAA's Storm Prediction Center logged four preliminary reports of tornadoes as of 2 pm Wednesday, along with 79 reports of damaging winds.


Video 1. View of the Adairsville, Georgia tornado of January 30, 2013. Note the blue power flashes as the tornado brings down power lines.

Record string of 219 days without a tornado death ends
Today's fatality ends the longest continuous stretch without a tornado death ever recorded in the U.S.--219 days. The last time the U.S. saw a tornado death was at Venus in Highlands County, Florida, from an EF-0 tornado associated with Tropical Storm Debby on June 24, 2012. The previous record was 197 straight days without a tornado death, which ended on February 28, 1987. Part of the reason for the long stretch without a tornado death during 2012 - 2013 was the relative lack of tornadoes. According to NOAA's Storm Prediction Center (SPC), the total number of tornadoes during 2012 was just 936. This is the first time since 2002 that fewer than 1000 tornadoes have been recorded. The jet stream was positioned unusually far north in Canada during much of 2012, which brought drought to much of Tornado Alley. It's tough to get tornadoes when you're experiencing near-record drought conditions and very few thunderstorms. Saskatchewan, Canada saw as many tornadoes in July 2012 as all of the U.S., thanks to the more northward position of the jet stream.


Figure 4. June 24, 2012: A tornado spawned by Tropical Storm Debbie crosses Lake Winterset in Winter Haven, Florida. Another tornado from Debbie on this day caused the last tornado death in the U.S., at Venus in Highlands County, Florida. Image credit: wunderphotographer whgator3.

Record moisture and rains
Today's severe weather outbreak was helped by record levels of January moisture, as a flow of unusually moist air rode northwards from the Gulf of Mexico, where water temperatures were about 0.5°F above average. Meteorologists use a term called "precipitable water" to discuss how much water vapor is in the atmosphere. Precipitable water is defined as how much rain would fall on the ground if one took a vertical slice of the atmosphere above a given location and condensed all the water vapor into rain. Precipitable water levels tend to be highest in the summer, since warm air holds more waver vapor, and can exceed two inches in the Midwest U.S. In winter, though, it is rare to see precipitable water values higher than one inch. However, precipitable water was well over an inch well into Canada, and three upper air stations--Detroit, MI, Lincoln IL, and Caribou, Maine--set all-time records for January moisture, and four other stations had their 2nd highest January moisture on record. From the 00Z January 30 to 00Z January 31 upper air balloon soundings taken at the 73 radiosonde stations in the contiguous U.S., we observed these record or near-record precipitable water values for January:

Detroit, MI: New Record: 1.21" Old record: 1.20" 1/11/75
Lincoln, IL: New record: 1.46" Old Record: 1.35" 1/12/60
Caribou, Maine: New Record: 1.21" (Ties old record of 1.21" 1/14/2005)
Alpena, MI: 2nd place, 0.99". First place: 1.01", 1/5/97
Buffalo, NY: 2nd place, 1.21". First place: 1.34", 1/15/95
Wilmington, OH: 2nd place, 1.44" First place: 1.51", 1/12/2005
Gray, ME: 2nd place, 1.36" First place: 1.38" 1/20/96

Green Bay (4th), Albany, NY (4th), Sterling, VA (4th), Shreveport (6th), Little Rock (3rd), Nashville, TN (10th), Chatham, MA (10th), and Maniwawi, Quebec (4th) all had top-ten January precipitable water values. Radiosonde data goes back to 1948.

The exceptional moisture led to record rains in many regions of the Midwest, with numerous locations setting daily precipitation records. Two airports recorded their wettest January day on record, including Madison, WI (1.84", previous record 1.80" on January 1, 1892) and Houghton Lake, MI (1.21", old record 1.08" on in 1938.) Top-five wettest January days in recorded history were also set at Muskegon, MI (2.48"), Marquette, MI (1.21"), and South Bend, IN (1.94".) Here where I live, in Southeast Michigan, being outside yesterday was like walking through a surreal white soup. Rains like nothing I've ever seen in January fitfully poured from the sky throughout the day, ponding up on the frozen ground. Eerie white fog swirled over the sodden snow drifts as thunder rumbled overhead in temperatures 25°F above average. What planet was this? The heavy rains of 1.60" that fell in 26 hours at the nearby Flint airport made this month our wettest January in recorded history, with 3.66" of precipitation.

Jeff Masters

Tornado Severe Weather

Record January warmth and moisture fueling April-like severe weather

By: JeffMasters, 3:42 PM GMT on January 30, 2013

An April-like severe weather outbreak accompanied by record warmth and atmospheric moisture continues today over the Southeast U.S., where a powerful cold front is creating severe thunderstorms, damaging winds, and tornadoes over the Southeast. NOAA's Storm Prediction Center logged four preliminary reports of tornadoes along with 264 reports of damaging winds on Tuesday, and another 71 reports of damaging winds between 7 am and 12 pm EST so far this Wednesday. A powerful tornado hit Adairsville, Georgia at 11:19 am EST this morning, and there are reports of major structural damage in the downtown district, with cars overturned (see eyewitness video here, with swear words.) The spring-like surge of warm air accompanying the severe weather outbreak has broken numerous daily high temperature records. The most notable heat record set Tuesday was the 91°F high in Corpus Christi, Texas, which tied their record for all-time warmest January temperature, set on January 30, 1971. The 62°F measured at Rockford, Illinois on Tuesday was just 1° shy of that city's all-time January temperature record. Tornado watches are posted for a wide swath of the Southeast today, from Alabama to Virginia, and numerous tornado warnings have been issued this morning. NOAA's Storm Prediction Center has placed most of the Southeast in their "Slight Risk" region for severe weather on Wednesday, a step down from the "Moderate Risk" potential issued on Tuesday for the Midwest.


Figure 1. A wild weather day in the Heartland: NOAA's Storm Prediction Center logged four preliminary reports of tornadoes on Tuesday, along with 264 reports of damaging winds.


Figure 2. Satellite image of the U.S. taken at 9:45 am EST January 30, 2013. Image credit: NASA/GSFC.


Figure 3. NOAA's Storm Prediction Center has placed most of the Southeast in their "Slight Risk" region for severe weather on Wednesday.

Record moisture and rains
Accompanying the exceptional January warmth yesterday were record levels of January moisture, as a flow of unusually moist air rode northwards from the Gulf of Mexico, where water temperatures were about 0.5°F above average. Meteorologists use a term called "precipitable water" to discuss how much water vapor is in the atmosphere. Precipitable water is defined as how much rain would fall on the ground if one took a vertical slice of the atmosphere above a given location and condensed all the water vapor into rain. Precipitable water levels tend to be highest in the summer, since warm air holds more waver vapor, and can exceed two inches in the Midwest U.S. In winter, though, it is rare to see precipitable water values higher than one inch. However, Tuesday night, precipitable water was well over an inch well into Canada, and two upper air stations--Detroit, MI and Lincoln IL--set all-time records for January moisture. From the 00Z Wednesday January 30 upper air balloon soundings taken at the 73 radiosonde stations in the contiguous U.S., we observed these precipitable water values for January:

Detroit, MI: New Record: 1.21" Old record: 1.20" 1/11/75
Lincoln, IL: New record: 1.46" Old Record: 1.35" 1/12/60
Alpena, MI: 2nd place, 0.99". First place: 1.01", 1/5/97
Buffalo, NY: 2nd place, 1.21". First place: 1.34", 1/15/95

Green Bay (4th), Shreveport (6th), and Little Rock (3rd) all had top-ten January precipitable water values. Radiosonde data goes back to 1948.

The exceptional moisture led to record rains in many regions of the Midwest, with numerous locations setting daily precipitation records. Two airports recorded their wettest January day on record, including Madison, WI (1.84", previous record 1.80" on January 1, 1892) and Houghton Lake, MI (1.21", old record 1.08" on in 1938.) Top-five wettest January days in recorded history were also set at Muskegon, MI (2.48"), Marquette, MI (1.21"), and South Bend, IN (1.94".) Here where I live, in Southeast Michigan, being outside yesterday was like walking through a surreal white soup. Rains like nothing I've ever seen in January fitfully poured from the sky throughout the day, ponding up on the frozen ground. Eerie white fog swirled over the sodden snow drifts as thunder rumbled overhead in temperatures 25°F above average. What planet was this? The heavy rains of 1.60" that fell in 26 hours at the nearby Flint airport made this month our wettest January in recorded history, with 3.66" of precipitation.

Jeff Masters

Severe Weather Extreme Weather Heat

April in January: spring-like severe weather and record warmth in the Midwest

By: JeffMasters, 3:19 PM GMT on January 29, 2013

The calendar says its January, but the atmosphere looks more like April over the Midwest U.S., where a spring-like surge of warm air is interacting with a strong low pressure system to create a dangerous severe weather situation. The warm air surging northwards has already broken high temperature records for the date in Chicago, where the mercury hit 61°F at 7 am CST; a tornado watch is posted for portions of Texas, Oklahoma, Kansas, and Arkansas. Golf-ball sized hail fell at three locations in Oklahoma already this morning, and a wind gust of 75 mph was reported in a thunderstorm near Omega, Oklahoma. NOAA's Storm Prediction Center has placed portions of Arkansas, Louisiana, Texas, Tennessee, Missouri, Alabama, Oklahoma, Illinois, Indiana, and Mississippi in their "Moderate Risk" region for severe weather on Tuesday. This is the first "Moderate Risk" forecast issued during 2013. The primary threat will be damaging thunderstorm winds, but we will also see tornadoes, with the potential for a few strong EF-2 and EF-3 twisters. The surge of warm moving northwards ahead of the cold front spawning today's severe weather is bringing in warmth unprecedented for January in some locations. Monday was the hottest January day on record in Topeka, Kansas, which hit 77°F. That's 36°F above average. and 3° warmer than their previous highest January temperature. Columbia, Missouri tied its all-time warmest January temperature, 77°. Kansas City (74°F) and Wichita (74°F) both fell 1° short of tying their all-time January hottest temperature records. Balloon soundings of the atmosphere taken last night showed moisture levels in the top 5% for a January day over much of the Midwest, and several stations may set all-time rainiest January day records today. One candidate is Flint Michigan, where a heavy thunderstorm moved in at 7:30 am, dumping 0.75" of rain. With another round of thunderstorms expected tonight, Flint is poised to break its record for rainiest January day in its history--the 1.34" that fell on January 18, 1949.


Figure 1. A crazy weather day for the U.S.: our severe weather map from 10 am EST Tuesday, January 29. Severe thunderstorms were occurring in Kansas and Oklahoma, flood watches were posted for Illinois, Michigan, Indiana, Ohio, and Wisconsin, and winter weather advisories, high wind advisories, and fire weather advisories were posted in other locations.


Figure 2. NOAA's Storm Prediction Center has placed portions of Arkansas, Louisiana, Texas, Tennessee, Missouri, Alabama, Oklahoma, Illinois, Indiana, and Mississippi in their "Moderate Risk" region for severe weather on Tuesday. This is the first "Moderate Risk" forecast issued during 2013.

Chicago's wild January weather ride continues
Chicago's craziest January in memory got even stranger today, when a surge of warm air pushed the temperature to 61°F at 7 am, breaking the previous high temperature record of 59°F for the date. Spring-like thunderstorms, accompanied by temperatures in the mid-60s are expected this afternoon--just a week after the city recorded a high temperature of 11°F and a low of -1°F (on January 22nd.) Chicago has been above 65°F in January just once in its history--on January 25, 1950, when the mercury hit 67°F. The average January high in the Windy City is 30°F, and today will be the 4th day the city has been 20 or more degrees warmer than that during January 2013. The roller coaster goes back downhill after the cold front moves through early on Wednesday, though--Chicago's high on Friday is expected to be near 15°F, with a morning low around 5°F. Chicago has also experienced record low snowfall this winter; the city got it's first 1-inch snowstorm of the season on Friday, when 1.1" fell at O'Hare Airport. This was the latest first 1-inch snow in city history, and ended a 335-day streak without a 1-inch snowstorm, the longest such streak since records began in 1872. Chicago has managed just 2.9" of snow during the winter of 2012 - 2013, which is 16" below average.

Chicago's roller coaster of temperatures doesn't compare, though, to what happened in Nowata, Oklahoma during the period February 10 - 17, 2011. A cold air mass combined with a fresh snow pack and calm winds allowed Nowata to hit a low of -31°F on February 10, 2011--the all-time coldest temperature ever recorded in Oklahoma. Gradual warming accelerated over the next week, and temperatures peaked at a record high of 79 degrees on February 17. According to the National Weather Service in Tulsa, Okla., this 110-degree temperature rise was the greatest change within seven days in Oklahoma history.


Video 1. In this video done by Peter Sinclair for the Yale Forum on Climate Change, I offer my thoughts on the roller coaster ride of temperatures in Michigan this winter, look back at the remarkable weather of 2012, and discuss what 2013 might bring. My main concern: drought.

Jeff Masters

Severe Weather Heat Magnus

Is it spring or is it winter? Wild roller coaster of temperatures for the U.S.

By: JeffMasters, 3:19 PM GMT on January 28, 2013

Is it spring or is it winter? The wild roller coaster ride of January 2013 weather continues this week, as Winter Storm Luna spreads snow, sleet and freezing rain across much of the Midwest and Northeast today, to be replaced by a spring-like surge of warm air nearly unprecedented in warmth and moisture for January. Temperatures in Oklahoma City have only reached 80° three times during January since 1890, but threaten to do so again today, and record-breaking high temperatures in the 70s are expected over much of Kansas and Missouri. Accompanying the exceptional January warmth will be near-record January moisture, as a flow of unusually moist air rides northwards from the Gulf of Mexico, where water temperatures are about 0.3°F above average. Meteorologists use a term called "precipitable water" to discuss how much water vapor is in the atmosphere. Precipitable water is defined as how much rain would fall on the ground if one took a vertical slice of the atmosphere above a given location and condensed all the water vapor into rain. Precipitable water levels tend to be highest in the summer, since warm air holds more waver vapor, and can exceed two inches in the Midwest U.S. In winter, though, it is rare to see precipitable water values higher than one inch. However, current model runs are predicting that precipitable water values on Tuesday evening will be near record values for January over much of the Central U.S. The high moisture will lead to widespread rainfall amounts of 1 - 2" over the Midwest. These rains are likely to cause flooding problems in areas where the rain falls on frozen soils with a significant snow pack. Flood watches are posted for much of Indiana, Southwest Lower Michigan, and Northwest Ohio, as a result. Here are the record January precipitable water values for some selected upper-air observation sites, along with the forecast precipitable water values for Tuesday evening from the latest run of the NAM model (thanks to Nick Wiltgen of TWC for compiling this):

Detroit, MI: Record: 1.20" at 00Z 1/11/75. Forecast: 1.2"
Nashville, TN: Record: 1.50" at 12Z 1/21/59. Forecast: 1.1"
Little Rock, AR: Record: 1.91" at 12Z 1/13/71. Forecast: 1.5"
Lincoln, IL: Record: 1.35" at 12Z 1/12/60. Forecast: 1.3"

Accompanying the heavy rain on Tuesday will be the threat of severe weather. NOAA's Storm Prediction Center has placed portions of Arkansas, Louisiana, and Mississippi in their "Moderate Risk" region for severe weather on Tuesday. This is the first "Moderate Risk" forecast issued during 2013. Severe thunderstorms with damaging wind gusts and tornadoes are likely in the Moderate Risk area.


Figure 1. Five-day predicted precipitation amounts for the period ending 7 am Saturday, February 2, 2013. Image credit: NOAA/HPC.


Figure 2. NOAA's Storm Prediction Center has placed portions of Arkansas, Louisiana, and Mississippi in their "Moderate Risk" region for severe weather on Tuesday. This is the first "Moderate Risk" forecast issued during 2013.

Dangerous air pollution episode finally eases in Utah
As I blogged about last week, clear skies, light winds, and a strong temperature inversion combined to create a dangerous air pollution episode in Northeast Utah in Salt Lake City and surrounding regions. However, over the weekend, a surge of warmer air and rain pushed into Utah, breaking up the temperature inversion, and bringing an end to the week-long pollution episode. In Salt Lake City, fine Particulate Matter less than 2.5 microns in diameter (also called PM 2.5) peaked at 59 micrograms per cubic meter on Saturday, nearly double the federal standard of 35 micrograms per cubic meter (averaged over 24 hours.) But by Sunday morning, PM 2.5 levels fell below 35 micrograms per cubic meter for the first time in over a week, allowing the city to finally breathe a little easier. In nearby Provo, Utah, the pollution had been much worse, with 24-hour average PM 2.5 levels more than triple the federal standard on Thursday morning, at 132 micrograms per cubic meter. On Sunday, air pollution levels in Provo also fell below the federal standard for the first time in over a week. With the forecast calling for snow through Tuesday and strong westerly winds building in, pollution levels should stay out of the red zone for at least the first part of this week. Brian Moench, an anesthesiologist and president of Utah Physicians for a Healthy Environment, estimates that poor air quality contributes to 1,000 to 2,000 premature deaths each year along Utah's Wasatch Front.


Figure 3. Observed air quality in North Provo, Utah, January 23 - 28, 2013. 24-hour average fine Particulate Matter less than 2.5 microns in diameter (also called PM 2.5) levels (black circles, top image) were in excess of the 35 micrograms per cubic meter U.S. standard (orange line) during the first part of the period, and peaked at 131 micrograms per cubic meter--more than 3 times the Federal standard--Thursday morning. The wind speed at the surface never rose above 6 mph (lower image, black dots) while the pollution was in excess of the federal standard, but on the 27th, the wind rose to 10 mph, helping flush out the pollution. Image credit: Utah DEQ.

Jeff Masters

Heat Extreme Weather Air and Water Pollution

Mighty North Atlantic low bombs to 930 mb

By: JeffMasters, 6:04 PM GMT on January 26, 2013

In the Northern Atlantic south of Iceland, an extratropical storm that brought up to 6" of snow to Maryland on Thursday has put on a remarkable burst of rapid intensification over the past 24 hours, with the center pressure dropping 58 mb in 24 hours. The Free University of Berlin, which names all major high and low pressure systems that affect Europe, has named the storm "Jolle." This meteorological "bomb" was analyzed with a central pressure of 988 mb at 12Z (7 am EST) Friday morning by NOAA's Ocean Prediction Center, and hit 930 mb by 7 am EST Saturday morning. The storm may deepen a few more millibars today, but it is close to maximum intensity. A 930 mb central pressure is what one commonly sees in Category 4 hurricanes, and is one of the lowest pressures attained by an Atlantic extratropical storm in recent decades. Since extratropical storms do not form eyewalls, the winds of the massive Atlantic low are predicted to peak at 90 mph (Category 1 hurricane strength), with significant wave heights reaching 52 feet (16 meters.) The powerful storm brought sustained winds of 52 mph, gusting to 72 mph, to Vestmannaeyjar, Iceland at 6 pm local time Saturday. Fortunately, the storm is expected to weaken dramatically before Jolle's core hurricane-force winds affect any land areas.


Figure 1. Winter Storm Jolle, as seen at 10 am EST January 26, 2013. Three hours prior to this image, Jolle was analyzed with a central pressure of 930 mb--one of the lowest pressures in recent decades for an Atlantic extratropical storm. Image credit: Navy Research Lab, Monterey.

According to wunderground's weather historian Christopher C. Burt's post on
Super Extratropical Storms, the all-time record lowest pressure for a North Atlantic extratropical storm is 913 mb, set on January 11, 1993, near Scotland's Shetland Islands. The mighty 1993 storm broke apart the super oil tanker Braer on a rocky shoal in the Shetland Islands, causing a massive oil spill.

Other notable Atlantic extratropical storms, as catalogued by British weather historian, Stephen Burt:

920.2 mb (27.17”) measured by the ship Uyir while she sailed southeast of Greenland on December 15, 1986. The British Met. Office calculated that the central pressure of the storm, which was centered some distance southeast of the ship, was 916 mb (27.05”).

921.1 mb (27.20”) on Feb. 5, 1870 measured by the ship Neier at 49°N 26°W (another ship in the area measured 925.5 mb)

924 mb (27.28”) on Feb. 4, 1824 at Reykjavik, Iceland (the lowest on land measured pressure in the North Atlantic)

925.5 mb (27.33”) on Dec. 4, 1929 by the SS Westpool somewhere in the Atlantic (exact location unknown)

925.6 mb (27.33”) on Jan. 26, 1884 at Ochtertyre, Perthshire, U.K. (the lowest pressure recorded on land in the U.K.)

For comparison’s sake, the lowest pressure measured on land during an extra-tropical storm in the United States (aside from Alaska) was 952 mb 28.10” at Bridgehampton, New York (Long Island) on March 1 during, the Great Billy Sunday Snowstorm.


Figure 2. Infrared satellite image of the North Atlantic Storm of January 11, 1993 at 0600Z when it deepened into the strongest extra-tropical cyclone ever observed on earth, with a central pressure of 913 mb (26.96”). Satellite image from EUMETSAT Meteosat-4.

Links
You can see a nice AVHRR image of the east side of the storm at the University of Bern. The raw MODIS pass is here.

The Meteorological Institute of Norway has a nice satellite animation of Jolle.

Wunderground's weather historian Christopher C. Burt's posts on Super Extratropical Storms and World and U.S. Lowest Barometric Pressure Records

Claudio Cassardo's January 23, 2013 post,
Very low minima of extratropical cyclones in North Atlantic

Read my story of what it was like to fly though a 936 mb Atlantic low pressure system on January 4, 1989.

Intense winter storms are expected to increase in number due to climate change
In my 2010 blog post, The future of intense winter storms, I discuss how evidence for an observed increase in intense wintertime cyclones in the North Atlantic is uncertain. In particular, intense Nor'easters affecting the Northeast U.S. showed no increase in number over the latter part of the 20th century. This analysis is supported by the fact that wintertime wave heights recorded since the mid-1970s by the three buoys along the central U.S. Atlantic coast have shown little change (Komar and Allan, 2007a,b, 2008). However, even though Nor'easters have not been getting stronger, they have been dropping more precipitation, in the form of both rain and snow. Several studies (Geng and Sugi, 2001, and Paciorek et al., 2002) found an increase in intense winter storms over both the North Atlantic, but Benestad and Chen (2006) found no trend in the western parts of the North Atlantic, and Gulev et al. (2001) found a small small decrease of intense winter storms in the Atlantic.

The U.S. Global Change Research Program (USGCRP), a scientific advisory board created by the President and Congress, concluded this in their 2009 U.S. Climate Impacts Report: "Cold-season storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent". The USGRP concluded that an increase of between four and twelve intense wintertime extratropical storms per year could be expected over the Northern Hemisphere by 2100, depending upon the amount of greenhouse gases put into the air (Figure 3). If we assume that the current climate is producing the same number of intense winter storms as it did over the period 1961-2000--about 53--this represents an increase of between 8% and 23% in intense wintertime extratropical storms. Two studies--Pinto et al. (2007) and Bengtsson et al. 2006--suggest that the more intense winter cyclones will affect only certain preferred regions, namely northwestern Europe and Alaska's Aleutian Islands. At least three other studies also find that northwestern Europe--including the British Isles, the Netherlands, northern France, northern Germany, Denmark and Norway--can expect a significant increase in intense wintertime cyclones in a future warmer world (Lionello et al., 2008; Leckebusch and Ulbrich 2004; and Leckebusch et al., 2006). None of these studies showed a significant increase in the number of intense Nor'easters affecting the Northeast U.S.


Figure 3. The projected change in intense wintertime extratropical storms with central pressures < 970 mb for the Northern Hemisphere under various emission scenarios. Storms counted occur poleward of 30°N during the 120-day season beginning November 15. A future with relatively low emissions of greenhouse gases (B1 scenario, blue line) is expected to result in an additional four intense extratropical storms per year, while up to twelve additional intense storms per year can be expected in a future with high emissions (red and black lines). Humanity is currently on a high emissions track. Figure was adapted from Lambert and Fyfe (2006), and was taken from Weather and Climate Extremes in a Changing Climate, a 2009 report from the the U.S. Global Change Research Program (USGCRP). The USGRP began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990, which called for "a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change".

Jeff Masters

Winter Weather Climate Change

North American cold wave winds down; Atlantic storm stronger than Sandy winding up

By: JeffMasters, 4:05 PM GMT on January 25, 2013

The January 2013 North American cold wave is winding down, after bringing five days of bitter cold to Canada and the Midwest and Northeast U.S. In the U.S., below-zero temperatures were recorded Friday morning in just six states east of the Rockies--half as many as on Thursday morning. The coldest spot was Saranac Lake in New York's Adirondack Mountains, which bottomed out at -18°F (-28°). In nearby Malone, NY, flooding is occurring, thanks to an ice jam on the Salmon River caused by this week's cold weather. The weather was a bit warmer on Mt. Washington, New Hampshire today, where the temperature of -17°F (-27°C) combined with a wind of 81 mph to create a wind chill of -61°F (-52°C). The most dangerous winter weather today will be due to the Wrath of Khan--a low pressure system traversing Tennessee and Kentucky has been named Winter Storm Kahn by TWC, and will bring as much as 0.5" of ice accumulation from eastern Tennessee and Kentucky through North Carolina and northern South Carolina, potentially causing major power outages. Snow will impact areas from the Ohio Valley through western Pennsylvania, West Virginia and Virginia, with 1" expected in D.C. and 1 - 3" in Baltimore.


Figure 1. A powerful extratropical storm with a central pressure of 984 mb begins to wind up about 500 miles east of Newfoundland, Canada, at 10 am EST January 25, 2013.

How low will it go? Massive Atlantic storm winding up
In the Northern Atlantic, an extratropical storm that brought up to 6" of snow to Maryland on Thursday is rapidly intensifying about 500 miles east of Newfoundland, Canada, and figures to become one of the most intense storms ever observed in the North Atlantic. This meteorological "bomb" was analyzed with a central pressure of 984 mb at 12Z (7 am EST) Friday morning by NOAA's Ocean Prediction Center; the GFS and ECMWF models both predict that the storm will deepen by 60 mb in 24 hours, reaching a central pressure of 924 - 928 mb by 7 am EST Saturday morning. This is the central pressure one commonly sees in Category 4 hurricanes, and is a very rare intensity for an extratropical storm to attain. Since extratropical storms do not form eyewalls, the winds of the massive Atlantic low are predicted to peak at 90 mph (Category 1 hurricane strength), with significant wave heights reaching 52 feet (16 meters.) Fortunately, the storm is expected to weaken dramatically before reaching any land areas, and will only be a concern to shipping. The intensification process will be aided by the strong contrast between the frigid Arctic air flowing off the coast of Canada from this week's cold blast, and the warm air lying over the warm waters of the Gulf Stream current. The ultimate strength of the storm will depend upon where the center tracks in relation to several warm eddies of the Gulf Stream along its path. According to wunderground's weather historian Christopher C. Burt's post on Super Extratropical Storms, the all-time record lowest pressure for a North Atlantic extratropical storm is 913 mb, set on January 11, 1993, near Scotland's Shetland Islands. The mighty 1993 storm broke apart the super oil tanker Braer on a rocky shoal in the Shetland Islands, causing a massive oil spill.

Other notable Atlantic extratropical storms, as catalogued by British weather historian, Stephen Burt:

920.2 mb (27.17”) measured by the ship Uyir while she sailed southeast of Greenland on December 15, 1986. The British Met. Office calculated that the central pressure of the storm, which was centered some distance southeast of the ship, was 916 mb (27.05”).

921.1 mb (27.20”) on Feb. 5, 1870 measured by the ship Neier at 49°N 26°W (another ship in the area measured 925.5 mb)

924 mb (27.28”) on Feb. 4, 1824 at Reykjavik, Iceland (the lowest on land measured pressure in the North Atlantic)

925.5 mb (27.33”) on Dec. 4, 1929 by the SS Westpool somewhere in the Atlantic (exact location unknown)

925.6 mb (27.33”) on Jan. 26, 1884 at Ochtertyre, Perthshire, U.K. (the lowest pressure recorded on land in the U.K.)

For comparison’s sake, the lowest pressure measured on land during an extra-tropical storm in the United States (aside from Alaska) was 952 mb 28.10” at Bridgehampton, New York (Long Island) on March 1 during, the Great Billy Sunday Snowstorm.


Figure 2. Infrared satellite image of the North Atlantic Storm of January 11, 1993 at 0600Z when it deepened into the strongest extra-tropical cyclone ever observed on earth, with a central pressure of 913 mb (26.96”). Satellite image from EUMETSAT Meteosat-4.

Intense winter storms are expected to increase in number due to climate change
In my 2010 blog post, The future of intense winter storms, I discuss how evidence for an observed increase in intense wintertime cyclones in the North Atlantic is uncertain. In particular, intense Nor'easters affecting the Northeast U.S. showed no increase in number over the latter part of the 20th century. This analysis is supported by the fact that wintertime wave heights recorded since the mid-1970s by the three buoys along the central U.S. Atlantic coast have shown little change (Komar and Allan, 2007a,b, 2008). However, even though Nor'easters have not been getting stronger, they have been dropping more precipitation, in the form of both rain and snow. Several studies (Geng and Sugi, 2001, and Paciorek et al., 2002) found an increase in intense winter storms over both the North Atlantic, but Benestad and Chen (2006) found no trend in the western parts of the North Atlantic, and Gulev et al. (2001) found a small small decrease in intense winter storms in the Atlantic.

The U.S. Global Change Research Program (USGCRP), a scientific advisory board created by the President and Congress, concluded this in their 2009 U.S. Climate Impacts Report: "Cold-season storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent". The USGRP concluded that an increase of between four and twelve intense wintertime extratropical storms per year could be expected over the Northern Hemisphere by 2100, depending upon the amount of greenhouse gases put into the air (Figure 3). If we assume that the current climate is producing the same number of intense winter storms as it did over the period 1961-2000--about 53--this represents an increase of between 8% and 23% in intense wintertime extratropical storms. Two studies--Pinto et al. (2007) and Bengtsson et al. 2006--suggest that the more intense winter cyclones will affect only certain preferred regions, namely northwestern Europe and Alaska's Aleutian Islands. At least three other studies also find that northwestern Europe--including the British Isles, the Netherlands, northern France, northern Germany, Denmark and Norway--can expect a significant increase in intense wintertime cyclones in a future warmer world (Lionello et al., 2008; Leckebusch and Ulbrich 2004; and Leckebusch et al., 2006). None of these studies showed a significant increase in the number of intense Nor'easters affecting the Northeast U.S.


Figure 3. The projected change in intense wintertime extratropical storms with central pressures < 970 mb for the Northern Hemisphere under various emission scenarios. Storms counted occur poleward of 30°N during the 120-day season beginning November 15. A future with relatively low emissions of greenhouse gases (B1 scenario, blue line) is expected to result in an additional four intense extratropical storms per year, while up to twelve additional intense storms per year can be expected in a future with high emissions (red and black lines). Humanity is currently on a high emissions track. Figure was adapted from Lambert and Fyfe (2006), and was taken from Weather and Climate Extremes in a Changing Climate, a 2009 report from the the U.S. Global Change Research Program (USGCRP). The USGRP began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990, which called for "a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change".

Links
Wunderground's weather historian Christopher C. Burt's posts on Super Extratropical Storms and World and U.S. Lowest Barometric Pressure Records

Claudio Cassardo's January 23, 2013 post, Very low minima of extratropical cyclones in North Atlantic

Jeff Masters

Winter Weather

U.S. deep freeze continues; dangerous air pollution episode in Utah

By: JeffMasters, 4:27 PM GMT on January 24, 2013

The January 2013 North American cold wave continued to bring bitter cold to much of Eastern Canada and the Midwest and Northeast U.S. this morning. In the U.S., below-zero temperatures were recorded Thursday morning in twelve states east of the Rockies. The most intense cold was centered near the Minnesota/Ontario border, where Embarrass, Minnesota hit -42°F (-41°C) and Crane Lake, Minnesota bottomed out at -36°F (-38°C). The coldest spot in Canada was in Souix Lookout, Ontario, about 100 miles north of International Falls, where the mercury fell to -40°F (-40°C.) The fun continued on the summit of Mt. Washington, New Hampshire this morning, where a temperature of -26°F (-32°C) combined with a wind of 71 mph to create a remarkable wind chill of -73°F (-58°C). A digression: back in 1986, when I taught weather forecasting at SUNY Brockport in New York, I worked with a meteorologist who used to work on top of Mt. Washington as a weather observer. He said it was standard practice back in the days he worked there to engage in a ritualistic prank whenever a new weather observer joined the staff. On the first day the new observer was there during one of Mt. Washington's classic hurricane-force wind events, he would be sent out with a safety harness and a can of paint to paint the observation platform. The unwitting observer would inch out into the hurricane winds, struggle to pry off the lid of the can of paint, and quickly discover the impossibility of painting during a hurricane--the powerful winds blowing over the top of the paint can would create a powerful Bernoulli Effect, levitating the paint out of the can and hurling all of the paint far downwind. The sheepish newbie weather observer would report back inside and ask, "you really didn't want me to paint the observing platform, did you?" to the sound of uproarious guffaws.


Figure 1. A cold day in New England: cold air flowing off of the New England coast creates thick stratocumulus clouds over the Atlantic Ocean in this true-color MODIS satellite image taken at 12:35 pm EST January 23, 2013. Image credit: NASA.

Dangerous air pollution in Utah
The most dangerous weather in the U.S. this week is occurring in the valleys of northern Utah, where clear skies, light winds, and a strong temperature inversion have combined to create a dangerous 6-day long air pollution episode. (A temperature inversion occurs when air temperature increases with altitude, acting as a stable lid preventing atmospheric mixing; inversions are common in mountain valleys when high pressure dominates.) It's been unusually cold during most of January in Northeast Utah, with Salt Lake City on track to have its 3rd coldest January on record. The cold weather has caused people to use their wood burning stoves more than usual, resulting in high emissions of smoke. More than 100 Utah doctors delivered a petition to state lawmakers on Wednesday, demanding that authorities immediately lower highway speed limits, curb industrial activity and make mass transit free for the rest of winter. "We're in a public-health emergency for much of the winter," said Brian Moench, an anesthesiologist and president of Utah Physicians for a Healthy Environment. He estimated that poor air quality contributes to 1,000 to 2,000 premature deaths each year along Utah's Wasatch Front.


Figure 2. View of a smoggy Salt Lake City taken at 2 pm MST January 23, 2013. Webcam image courtesy of University of Utah/TimeScience.

Winds have remained below 6 mph for six straight days in Northern Utah, allowing fine Particulate Matter less than 2.5 microns in diameter (also called PM 2.5) to build up to unhealthful levels. PM 2.5, also known as particle pollution, is a complex mixture of extremely small dust and soot particles that lodge in the lungs and cause large increases in hospital admissions and excess mortality during severe air pollution episodes like this one. The federal standard for PM 2.5 is 35 micrograms per cubic meter, averaged over 24 hours. In Salt Lake City, fine particle air pollution has been above the federal standard for six consecutive days, with a peak value of 91 micrograms per cubic meter on January 19. In nearby Provo, Utah, the pollution has been much worse, with 24-hour average PM 2.5 levels more than triple the federal standard on Thursday morning, at 131 micrograms per cubic meter. If the PM 2.5 levels go above 150 micrograms per cubic meter, this will be in the "Very Unhealthy" category as defined by EPA. At this pollution level, the entire population is likely to be affected, and health warnings of emergency conditions are issued. Compounding the air pollution woes in Provo are high levels of nitrogen dioxide gas, which peaked at 98 ppb on Tuesday, just below the 100 ppb federal standard. Light winds and a strong temperature inversion will continue today, and freezing rain fell over much of the Salt Lake City area this morning, turning the roads into skating rinks, resulting in dozens of traffic accidents. Fortunately, the forecast for Provo calls for snow and rain this weekend due to a low pressure system, and the rain and winds associated with this low should be able to reduce air pollution levels significantly.


Figure 3. Observed air quality in North Provo, Utah, January 19 - 24, 2013. 24-hour average fine Particulate Matter less than 2.5 microns in diameter (also called PM 2.5) levels (black circles, top image) were in excess of the 35 micrograms per cubic meter U.S. standard (orange line) during the entire period, and peaked at 131 micrograms per cubic meter--more than 3 times the Federal standard--Thursday morning. Levels of toxic nitrogen dioxide (yellow dots) peaked at 98 ppb, just below the U.S. standard of 100 ppb, on January 22. Note that during the entire 5-day period pictured here, the wind speed at the surface never rose above 6 mph (lower image, black dots.) Image credit: Utah DEQ.

Jeff Masters

Winter Weather Air and Water Pollution

Bitter cold and heavy lake effect snows continue in the Midwest and Northeast U.S.

By: JeffMasters, 4:18 PM GMT on January 23, 2013

A classic January North American cold wave continues to bring bitter cold to much of Eastern Canada and the Midwest and Northeast U.S., and heavy lake effect snows to the shores of the Great Lakes. The intense cold was centered near the Ontario/Quebec border this Wednesday morning, where a numbingly low temperature of -45°F (-43°C) was observed at Rouyn, Quebec. The 2 mph wind created a wind chill of -54°F (-48°C). One other station in Canada, Pointe Claveau, Quebec also reported a wind chill of -54°F, thanks to a temperature of -19°F (-28°C) and a wind of 38 mph. In the U.S., below-zero temperatures were recorded Wednesday morning in eleven states east of the Rockies. The coldest air was centered over Northern Maine, where the temperature plummeted to -36°F (-37°C) at Estcourt Station. No doubt the most fun place to be in all of North America this morning was on top of Mt. Washington, New Hampshire, where the temperature of -35°F (-37°C) combined with a wind of 69 mph to create a truly astonishing wind chill of -85°F (-65°C)!

The weather was a bit less extreme, but nonetheless notably cold, in Washington DC, which bottomed out at 15°F this morning--the coldest it has been there in nearly four years, since March 3, 2009. DC hit a high of just 32°F on Tuesday--the first high temperature of 32° or below in DC since January 22, 2012. The forecast calls for DC to remain below freezing for a 6-day period. According to Ian Livingston of the Capital Weather Gang, the last time D.C. had more than four consecutive days below freezing was during the winter of 2004 - 2005, when the city had a 6-day below-freezing streak. Here in Southeast Michigan where I live, it got below zero for the first time in nearly two years on Tuesday. During my late afternoon cross-country ski adventure on the frozen lake that I live by, I alternated between marveling at the beauty of the swirling "snow devils" kicked up by the gusts of 20 mph, and quailing before their brutal impact in the 7°F cold. I prefer it about 20° warmer for my cross-country ski adventures, thank you!


Figure 1. True-color MODIS satellite image of Tuesday's lake effect snowstorms taken at 3:20 pm EST January 22, 2013. The most concentrated band of snow was affecting the east shore of Lake Ontario (far right of image) near Oswego, New York. Up to 32" of snow fell in 24 hours in this band. Note the thin streaks of snow to the southwest of Lake Michigan in north central Illinois. According the the National Weather Service in Chicago, these bands of snow were lake-effect induced, but not from Lake Michigan--the snow was due to cold air flowing over warm waters in power plant cooling ponds. Image credit: NASA.

The frigid Arctic air blasting over the unusually warm Great Lakes have created more than a foot of lake effect lake effect snows in the lees of Lake Erie, Lake Ontario, and Lake Michigan. Bennetts Bridge, in Oswego County, New York, got a truly prodigious dumping from a Lake Ontario snow band--32" of snow in the 24 hours ending at 7 am Tuesday. As of 9 am EST Wednesday, here were the top snow amounts so far from this lake effect snow event:

38" Fulton, NY
36.5" Phoenix, NY (7 miles NNE)
32" Bennetts Bridge, NY
24.8" Lacona, NY
24.8" Ripley, NY
19" Pulaski, NY
18" Sterling, NY
18" Camden, NY
13" Perrysburg, NY
12" Sinclairville, NY
12" Collins, NY

Snow on the ground:
14.5" Kirtland, OH
13.5" Montville, OH
16" Fairview, PA
16" Franklin Center, PA
13" Erie, PA (6 miles SW of town)

According to wunderground's weather historian, Christopher C. Burt, some world-record point snowfalls from the Great Lakes region include:

7” in 30 minutes at West Seneca, NY on Dec. 2, 2010
12” in 1 hour at Copenhagen, New York on Dec. 2, 1966
17.5” in 2 hours at Oswego, New York on Jan. 26, 1972
22” in 3 hours at Valparaiso, Indiana on Dec. 18, 1981
51” in 16 hours at Bennetts Bridge, New York on Jan. 17-18, 1959
77” in 24 hours at Montague Township on the Tug Hill Plateau of New York on Jan. 11-12, 1997

Although the current Arctic air outbreak is severe, it has broken very few cold temperature records. No airport weather stations east of the Rockies set minimum low temperature records for the date on either Monday or Tuesday, though a number of stations did set their record for the coldest maximum temperature for the date Tuesday. These stations included Marquette, MI (-3°) , Flint, MI (10°), Muskegon, MI (10°), Dayton, OH (15°), and South Bend, IN (9°). The place to be Tuesday was the Southwest U.S., where Phoenix (81°), Tucson (81°), and San Diego (80°) all set record highs for the date.

Heavy lake effect snows are increased by warm waters, lack of ice
This week's exceptional lake effect snows were substantially increased by near-record warm Great Lakes water temperatures. These conditions were caused by the fact that 2012 was the warmest year on record over much of the Great Lakes region. According to NOAA's Great Lakes Environmental Research Laboratory (GLERL), water temperatures averaged over Lake Ontario are currently about 3°F above average, and range from 2 - 3°F warmer than average over Lake Superior, Lake Michigan, and Lake Huron. Lake Erie, which is shallow and heats up and cools down relatively quickly, is only about 0.2°F above average. Warm air holds more water vapor, and the largest lake effect snow storms tend to occur early in November and December when the lakes are at their warmest, and there is more moisture available to make heavy snow. If the lakes are frozen, they generate very little in the way of lake effect snow, since little moisture can escape upwards from the ice. At the beginning of this week, ice cover on the Great Lakes was below average, which helped generate a larger lake effect snow event than usual for January. Ice cover on North America's Great Lakes--Superior, Michigan, Huron, Ontario, and Erie--has declined 71% since 1973, according to a 2012 study published in the Journal of Climate by researchers at NOAA's Great Lakes Environmental Research Laboratory. The biggest loser of ice during the 1973 - 2010 time period was Lake Ontario, which saw an 88% decline in ice cover. During the same time period, Superior lost 79% of its ice, Michigan lost 77%, Huron lost 62%, and Erie lost 50%. The loss of ice is due to warming of the lake waters, which could be due to a combination of global warming and natural cycles, the researchers said. Winter air temperatures over the lower Great Lake increased by about 2.7°F (1.5°C) from 1973 - 2010, and by 4 - 5°F (2.3 - 2.7°C) over the northern Lakes, including Lake Superior. Lake Superior's summer surface water temperature warmed 4.5°F (2.5°C) over the period 1979 - 2006 (Austin and Colman 2007). During the same period, Lake Michigan warmed by about 3.3°F (1.7°C), Lake Huron by 4.3°F (2.4°C), and Lake Erie showed almost no warming. The amount of warming of the waters in Lakes Superior, Huron, and Michigan is higher than one might expect, because of a process called the ice-albedo feedback: when ice melts, it exposes darker water, which absorbs more sunlight, warming the water, forcing even more ice to melt. This sort of vicious cycle is also largely responsible for the recent extreme loss of Arctic sea ice in summer. The loss of Great Lakes ice has allowed much more water to evaporate in winter, resulting in lower lake levels. As I blogged about last week, water levels on Lake Michigan and Lake Huron were at their lowest December water levels on record, and are predicted to set an all-time low by March.



Figure 2. Current Great Lakes ice coverage on January 23, 2013 (top) compared to the average Great Lakes ice coverage during 1973 - 2002 for the January 22 - 28 time period (bottom). This year's near-record warm water temperatures led to below-average ice coverage on the lakes until mid-January, but this week's cold blast has helped them catch up to near-normal ice cover. Image credit: Great Lakes Environmental Research Laboratory (GLERL).

Links
Andrew Freedman of Climate Central has an excellent post on how this week's cold blast was triggered by a warming of the stratosphere that began in early January.

Wunderground's Lee Grenci has detailed description on how these Sudden Stratospheric Warming events occur.

My post last week, Drought predicted to continue though April; record low Lake Michigan water levels.

References
Austin, J. A., and S. Colman, 2007, "Lake Superior summer water temperatures are increasing more rapidly than regional air temperatures: A positive ice-albedo feedback," Geophys. Res. Lett., 34, L06604, doi:10.1029/2006GL029021.

Wang, J., X. Bai, H. Hu, A.H. Clites, M.C. Colton, and B.M. Lofgren, 2012, "Temporal and spatial variability of Great Lakes ice cover, 1973-2010," Journal of Climate 25(4):1318-1329 (DOI:10.1175/2011JCLI4066.1)

Jeff Masters

Winter Weather

Major cold blast, epic lake effect snows hit North America

By: JeffMasters, 4:36 PM GMT on January 22, 2013

A classic January North American cold wave has plunged much of the continent into the deep freeze and brought epic lake effect snows to the shores of the Great Lakes. The intense cold was centered over central Ontario this Tuesday morning, where a remarkable low temperature of -49°F (-45.0°C) was observed at Lansdowne House, Ontario. This was the coldest temperature measured at a major observing station in all of North America today. In the U.S., below-zero temperatures were recorded Tuesday morning in eleven states east of the Rockies. The coldest air was centered over Northern Minnesota, where the temperature plummeted to -35°F (-37°C) at Crane Lake at 7 am CST, with calm winds. The coldest wind chills were observed in Southern Manitoba, Northern Wisconsin, and Michigan's Upper Peninsula, where the clockwise flow of air around a high pressure system centered over Iowa brought bitter cold winds. The wind chill at Ironwood, Michigan hit -42°F at 7 am this morning, thanks to a temperature of -17°F combined with a wind of 17 mph. The wind chill hit -40° F (-40°C) at Rhinelander, Wisconsin.


Figure 1. Visible satellite image from 10:45 am EST January 22, 2013 shows multiple bands of lake effect snow streaming off of Lake Erie (lower left), and one very concentrated band of snow affecting the east shore of Lake Ontario over Oswego, New York (center right of image.) Image credit: NOAA.


Figure 2. Radar image of the band of very heavy lake effect snow affecting Oswego, NY (circle with a "+" symbol in it) at 11:08 EST January 22, 2013. The echo intensity of 25 dBZ (light blue colors) is very intense for a snow storm, and snowfall rates of up to 5" per hour may be occurring in this band.

The frigid Arctic air blasting over the unusually warm Great Lakes have created very heavy lake effect snows, and snowfall amounts in excess of a foot have hit the snow belts in the lee of Lake Erie and Lake Ontario in Ohio, Pennsylvania, and New York. The heaviest snows on Tuesday morning were falling along the eastern shore of Lake Ontario in New York, where the National Weather Service is warning that snowfall amounts of 2 - 4" per hour, possibly up to 5" per hour, will occur today. More than a foot of snow is also expected in along the shores of Lake Superior near Munising over the next day. As of 7 am EST Tuesday, here were the top snow amounts so far from this epic lake effect snow event:

18" Ripley, NY
13" Perrysburg, NY
12.7" Lacona, NY
12" Sinclairville, NY
12" Collins, NY

17" Fairview, PA
15" Colt Station, PA
14" Erie, PA (6 miles SW)
13" Girard, PA
12" Millcreek TWP, PA

13" Geauga, OH
13" Montville, OH
12" Thompson, OH
12" Montville, OH

Snow in southern Ohio on Monday created whiteout conditions near Cincinnati, causing a 79-car pile-up on I-275, and a 50-car pile-up on I-75. The CIMSS Satellite Blog shows the conditions during the event nicely.

Although the current Arctic air outbreak is severe, it has broken very few records. Only 11 daily minimum low temperature records were tied or broken in the U.S. on Monday; none of these records were set at stations east of the Rockies. In fact, there were more daily high temperature records set in the U.S. yesterday--fifteen in all, including new high temperature records at Los Angeles, Burbank, and Shasta in California.

Jeff Masters

Winter Weather

Coldest air in nearly two years hits the Midwest U.S.

By: JeffMasters, 5:08 PM GMT on January 21, 2013

A blast of Arctic air more intense than anything experienced during the winter of 2011 - 2012 has descended over the Midwest U.S., bringing the coldest temperatures in nearly two years. The low hit -2°F Monday morning in Des Moines, Iowa, marking the first day since February 10, 2011 that Des Moines had dropped below zero. The 710 consecutive days the city had gone without reaching 0°F was the longest such streak on record (previous record: 368 straight days, beginning January 23, 1954.) In Minneapolis, the mercury dropped to -10°F Monday morning, the coldest day since February 10, 2011. With the high temperature not expected to get above zero Monday, the city will likely snap its record-long streak of just over four years without a high temperature above 0°F. The last time the high temperature at the Minneapolis airport was below zero was on January 15, 2009, when the thermometer climbed to only -6°F. The previous longest such streak since record keeping began in 1872 was a 3.1 year streak that ended in January 2004. Strong winds accompanying today's cold blast have dropped the wind chill to a dangerously cold -40 to -50°F across much of Minnesota and North Dakota. The wind chill bottomed out at -51°F at Langdon, North Dakota at 4:35 CST Monday morning, thanks to a temperature of -22° combined with a wind of 17 mph. The wind chill hit -46°F at nearby Devils Lake and -51° at Hamden. The lowest wind chill in Minnesota was at Le Center: -43°F. Brr!

Jeff Masters

Winter Weather

Drought predicted to continue though April; record low Lake Michigan water levels

By: JeffMasters, 6:14 PM GMT on January 18, 2013

Rain and snow from the a series of winter storms that have swept across the nation so far in 2013 have put only a slight dent in the Great Drought of 2012 - 2013, and the drought is likely to extend at least until late April, according to the latest U.S. Drought Monitor report and NOAA Seasonal Drought Outlook, issued Thursday. The area of the contiguous U.S. covered by moderate or greater drought began 2013 at 61%, and is almost unchanged as of January 15, at 59%. According to NOAA's monthly State of the Drought report, the drought peaked during July 2012, when 61.8% of the contiguous U.S. was covered by moderate or greater drought. This made the 2012 drought the greatest U.S. drought since the Dust Bowl year of 1939, when 62.1% of the U.S. was in drought. The 2013 drought will maintain its grip over the U.S. into February, according to the latest 15-day precipitation forecast from the GFS model, which predicts a much below-average chance of precipitation across the large majority of the drought region during the next two weeks. These dry conditions will continue to cause problems for shipping on the Mississippi River, where barge traffic has been limited by near-record low water. However, the river level at St. Louis has risen about a foot since the beginning of the year, and the Army Corps of Engineers blasted away rock formations on the river bottom near Thebes, Illinois over the past two weeks, which should allow limited barge traffic to continue on the river at least through the end of January. The Corps now believes that will be able to keep shipping on the Mississippi River open into the summer. The latest NOAA river level forecast calls for the river to fall below -5' by January 30, which would be one of the five lowest water levels on record for St. Louis.


Figure 1. Predicted 7-day precipitation for the period ending on Friday, January 25. Less than 10% of the U.S. drought regions are predicted to receive as much as 0.5" of precipitation (dark green color.) Image credit: NOAA.


Figure 2. NOAA's January 17 Seasonal Drought Outlook calls for drought to persist over at least 70% of the U.S. drought area through the end of April. The drought is expected to ease some along its northern and eastern edges, but new areas of drought are predicted to develop over Texas, California, and the Southeast U.S.


Figure 3. The latest NOAA river level forecast calls for the Mississippi River to fall below -5' by January 30. The river's lowest level on record, -6.2', occurred in January 1940, after the great Dust Bowl droughts of the 1930s.

Lake Michigan and Lake Huron hit all-time record low water levels for January
Low water is also a problem on Lake Michigan and Lake Huron. After setting an all-time record low for the month of December, water levels have continued to fall, are are now 1" below the record-lowest January water level, observed in January 1965, according to the Army Corps of Engineers. Water levels on Lake Michigan, Lake Huron, and Lake Superior are predicted to fall 1 - 2" over the next month, due to below average precipitation. Lake Michigan and Lake Huron are already at 576.0', so if this forecast verifies, they will set the record for their all-time monthly level, the 576.05' level of March 1964. Lake Superior is still 6" above its all-time low water level, so will not set a new record. Below average ice cover, which allows increased evaporation, is contributing to the low water levels. The low ice cover is due to the record warm year of 2012, which has left the lakes 2 - 3°C above average in temperature, as of January 8. Barges on the lakes are being forced to carry reduced loads due to the low water. Great Lakes water level data goes back to 1918.


Figure 4. The water level on Lake Huron and Lake Michigan measured during 2012 - 2013 (red line) hit an all-time December monthly low during December 2012, beating the record set in 1964. The predicted water levels for January - March call for record lows all three months. Image credit: Army Corps of Engineers.

Long-term drought outlook
NOAA's January 17 Seasonal Drought Outlook calls for drought to persist over at least 70% of the U.S. drought area through the end of April. The drought is expected to ease some along its northern and eastern edges, but new areas of drought are predicted to develop over Texas, California, and the Southeast U.S. I don't see any signs of a shift in the fundamental large-scale atmospheric flow patterns coming, and it is good bet that drought will be a huge concern as we enter spring. NOAA's Climate Prediction Center predicts an increased chance of drier than average conditions over southwestern portions of the drought region during the coming three months. In general, droughts are more likely in the Midwest U.S. when warmer than average ocean temperatures prevail in the tropical Atlantic, with cooler than average ocean temperatures in the tropical Eastern Pacific (La Niña-like conditions.) This is what we had in during most of 2012, and continue to have in 2013. In fact, the equatorial tropical Pacific has cooled in recent weeks to 0.6°C below average (as of January 14). This is similar to the ocean temperatures seen in the spring of 2012, just before the Great Drought of 2012 began. Most of the U.S. drought region needs 3 - 9" of precipitation to pull out of drought.

Drought links:
My post on Lessons from 2012: Droughts, not Hurricanes, are the Greater Danger discussed how drought is our greatest threat from climate change.

Ricky Rood blogs about the Dust Bowl

Wunderground weather news
Wunderground's Angela Fritz has put together a weather news feature that provides a selection of recent media articles on major global weather events. For example, Sydney, Australia's biggest city, set it's all-time heat record today, with the temperature peaking at 45.8 degrees Celsius (114.4 Fahrenheit). The old record, of 45.3 C (113.5 Fahrenheit), was set in January 1939. Also, heavy snow hit Britain today, and a dock from Japan showed up on the coast of Washington.

Featured blogger Lee Grenci has a new post today on the incredibly intense 932 mb low that affected the Aleutian Islands yesterday.

Have a great weekend, everyone!

Jeff Masters

Drought

DC snowstorm not enough for a white inauguration; extreme heat in Southern Hemisphere

By: JeffMasters, 5:18 PM GMT on January 17, 2013

It's snowing in Mississippi and Alabama, thanks to strengthening Winter Storm Iago. Iago is poised to bring up to a foot of snow across the Central Appalachians, and 3 to 8 inches of snowfall across Mid-Atlantic metro areas including cities such as Richmond, Raleigh and Roanoke. Washington DC is on the northern edge of the accumulating snow, and is only expected to see an inch of wet, sloppy accumulation. With sunny skies and high temperatures expected to be in the mid-40s over the weekend in the nation's capital, it appears unlikely that we'll see a white Inauguration Day on Monday, when President Obama is scheduled to be sworn in at noon. Temperatures should be in the low 30s at the time, but there is a 30% chance of some snow flurries brightening up the scene. According to the National Weather Service's Presidential Inaugural Weather web site, the normal high temperature for 12 pm EST on January 21 is 37°F, with partly cloudy skies, a 10 mph wind, and a wind chill of 31°F. During President Obama's 2009 inauguration, the noon temperature was 28°F under partly sunny skies, with a wind chill near 15°F due to breezy northwest winds of 15 mph, gusting to 25 mph.


Figure 1. Snow in Starkville, Mississippi, on January 17, 2013. Image credit: wunderphotographer JDA.

Famous Inauguration Day weather events
The most infamous inauguration day weather occurred in 1841, when President William Henry Harrison was sworn in. Harrison, 68, gave a one hundred minute speech in cold, wet weather without wearing a coat or a hat. He spent a lot of time talking about ancient Rome to a mostly unappreciative audience. The new president then attended a parade and three inaugural balls, possibly in the same wet clothing he wore outside during the speech. Within a month, Harrison was dead from pneumonia and pleurisy. While there's a debate about what exactly killed Harrison, the inauguration was linked to his death.

Almost as bad--1853: President Franklin Pierce was sworn into office on another cold and snowy day. He awoke to heavy snow in the morning which continued until about 11:30 am. Skies looked to be brightening by noon. Shortly after Pierce took his oath of office, as he began his inaugural address, snow started again. It came down heavier than ever dispersing much of the crowd and ruining plans for the parade. Abigail Fillmore, First Lady to the outgoing President Millard Fillmore, caught a cold as she sat on the cold, wet, exposed platform during the swearing-in ceremony. The cold developed into pneumonia and she died at the end of the month.

Worst Weather Day--1909:  President William H. Taft's ceremony was forced indoors due to a storm that dropped 10 inches of snow over the Capital city. The snow and winds began the day before. Strong winds toppled trees and telephone poles. Trains were stalled and city streets clogged. All activity was brought to a standstill. Sanitation workers shoveled sand and snow through  half the night. It took 6,000 men and 500 wagons to clear 58,000 tons of snow and slush from the parade route. See pictures. Despite the freezing temperatures, howling wind, snow, and sleet, a large crowd gathered in front of the Capitol to view the inauguration, but the weather forced the ceremony indoors. Just after the swearing-in, the snow tapered off.

Warmest January Inauguration: 1981, Ronald Reagan; 55°F under mostly cloudy skies.

Coldest Inauguration: 1985, Ronald Reagan. His second swearing-in ceremony on January 21 had to be held indoors and the parade was canceled. The outside temperature at noon was only 7°F. The morning low was 4° below zero and the daytime high was only 17°. Wind chill temperatures during the afternoon were in the -10 to -20°F range.



Figure 2. Photo taken in front of Presidential Reviewing stand during President Taft's inauguration in 1909. Image credit: National Weather Service, Baltimore/Washington D.C.

Wicked hot in South Africa
The mercury soared to 48.4°C (119°F) in Vioolsdrif, South Africa on Wednesday January 16, marking the third hottest temperature ever recorded in the Southern Hemisphere portion of Africa, according to weather records researcher Maximiliano Herrera. The two hottest temperatures in the Southern Hemisphere portion of Africa were also measured at Vioolsdrif: a 48.8°C (119.8 °F) reading on Jan 3, 1993, and a 48.7°C reading in January, 1995. Clouds moved in yesterday just as the temperature was peaking in Vioolsdrif, or else a new record would have been set.

Another super-hot day in Australia
Unusually hot weather continues in Australia, where a two-week heat wave has brought some of the hottest weather in the nation's history, including the Southern Hemispheres's hottest temperature measured so far in 2013--a 49.6°C (121.3°F) reading from Moomba Airport in South Australia on January 12. The record for all-time hottest temperature in Australian history is the 50.7°C (123.3°F) reading on 2 January 1960 at Oodnadatta, South Australia. The nation's average high temperature exceeded 102°F (39°C) for seven consecutive days January 2 - 8, 2013--the first time that has happened since record keeping began in 1910. To put this remarkable streak in perspective, the previous record of four consecutive days with a national average high temperature in excess of 102°F (39°C) has occurred once only (1973), and only two other years have had three such days in a row--1972 and 2002. Part of the reason for the extreme heat this year is the presence of a stubborn ridge of high pressure that has delayed the onset of the yearly monsoon by three weeks. Extremely hot high temperatures reaching into the mid-40s over eastern Western Australia, South Australia, western Queensland and large parts of Victoria and NSW are expected today (Thursday) and tomorrow (Friday), causing continued problems for firefighters. However, the monsoon is now pushing southwards across Australia, and is expected to bring cooler and wetter conditions to northern Australia this weekend. The monsoon will gradually work its way southwards next week, helping flush out the heat that has accumulated in Australia's interior.

Jeff Masters

Winter Weather Heat

2012: Earth's 10th warmest year on record, and warmest with a La Niña

By: JeffMasters, 7:04 PM GMT on January 15, 2013

It was another top-ten hottest year on record during 2012, which ranked as the 10th warmest year since records began in 1880, NOAA's National Climatic Data Center said today. NASA rated 2012 as the 9th warmest on record. Including 2012, all 12 years to date in the 21st century (2001–2012) rank among the 14 warmest in the 133-year period of record. Only one year during the 20th century--1998--was warmer than 2012. The year 2012 was the warmest year on record when a La Niña event was present. Global land temperatures were the 7th warmest on record, and ocean temperatures were the 10th warmest. Global satellite-measured temperatures in the lower atmosphere were the 9th or 11th warmest in the 34-year record, according to UAH and RSS, respectively. Following the two wettest years on record (2010 and 2011), 2012 saw near average precipitation on balance across the globe. In a NASA Press Release today, climate scientist Gavin Schmidt said, "One more year of numbers isn't in itself significant. What matters is this decade is warmer than the last decade, and that decade was warmer than the decade before. The planet is warming. The reason it's warming is because we are pumping increasing amounts of carbon dioxide into the atmosphere."


Figure 1. Departure of global temperature from average for 2012. The continental U.S. and the eastern 2/3 of Canada were Earth's warmest regions, relative to average. Image credit: NOAA's National Climatic Data Center.

Global extremes of 2012
Weather records researcher Maximiliano Herrera has put together a list of global extremes for 2012, and 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. Here, then, is Maximiliano's list of 2012 global extremes:

Hottest temperature in the world in 2012: 53.6°C (128.5°F) in Sulaibiya, Kuwait, July 31
Coldest temperature in the world in 2012: -84.2°C (-119.6°F) at Vostok, Antarctica, September 16
Hottest temperature in the Southern Hemisphere: 47.5°C (117.5°F) at Birdsville, Australia, January 7
Coldest temperature in the Northern Hemisphere: -63.1°C (-81.6°F) at Summit, Greenland, December 28
Highest annual precipitation: Cherrapunji, India, 13364 mm (526")
Lowest annual precipitation:  Several stations in Southern Egypt saw not even a trace of precipitation

All-time world record warm minimum temperature tied: 41.7°C (107°F), Death Valley (USA), July 12
All-time world record highest 24-hour average temperature: 47.5°C (117.5°F), Death Valley (USA), July 11-12
World record high temperature in an island: 51.8°C (125.2°F), Failaka Island, Kuwait, July 31
World record high temperature on a coast: 52.1°C (125.8°F), Kuwait City, Kuwait, July 31
World record highest temperature with rain: 46.1°C (115°F), Needles (USA), August 13
World record for lowest humidity with rain: 11%, Needles (USA), August 13


Figure 2. True-color MODIS satellite image of California and Arizona taken at 1:25 pm PDT August 13, 2012. Developing thunderstorms surround Needles, CA, and the line of clouds to the southwest of the city would develop into a thunderstorm that brought rain to the city at 4 pm PDT, at a temperature of 115°F and a relative humidity of 11%--both world records. Image credit: NASA.

New country and territory hottest temperature records set in 2012
Five nations and two territories tied or set their hottest temperature readings in recorded history during 2012; no coldest all-time national records were set. For comparison, Seven countries and one territory set all-time hottest temperature records in 2011, and one nation set an all-time coldest temperature record. The most all-time national heat records in a year occurred in 2010, when twenty nations and one territory did so. Here are the 2012 national heat records:

Morocco recorded its hottest temperature on record on July 17, 2012 in Marrakech, when the mercury hit 49.6°C (121.3°F).

Kuwait recorded its hottest temperature on record on July 31, 2012 in Sulaibya, when the mercury hit 53.6°C (128.5°F). This surpasses the highest undisputed temperature ever recorded in Asia--the 53.5°C (128.3°F) measured at Moen Jo-Daro, Pakistan on May 26, 2010. The only higher temperature ever measured in Asia was a 54°C (129.2°F) reading from Tirat Tsvi, Israel on June 22, 1942. The Israeli Met Office pursued an investigation of the record in 2012 (prompted by an inquiry from the WMO and wunderground's weather historian Christopher C. Burt), and concluded that the record was valid. However, they have refused to make public the details leading to their conclusions, and until they do so, the record remains suspect.

Moldova recorded its hottest temperature on record on August 7, 2012 in Falesti, when the mercury hit 42.4°C (108.3°F).

Montenegro tied its hottest temperature on record on August 8, 2012 in Danilovgrad, when the mercury hit 44.8°C (112.6°F).

The Czech Republic recorded its hottest temperature on record on August 20, 2012 in Dobrichovice, when the mercury hit 40.4°C (104.7°F).

The territory of Hong Kong tied its hottest temperature on record on July 21 on Ping Chau Island, when the mercury hit 37.7°C (99.9°F).

The Sprska Republic set a new territorial high of 42.8°C (109°F) on August 24 at Visegrad.

New U.S. State Records set in 2012
New state record high: South Carolina, at  Columbia University WS and Johnston, 45.0°C (113°F), June 29
State record high temperature tied: Colorado, at Las Animas, 45.6°C (114°F), June 23

Wunderground's weather historian Christopher C. Burt maintains a database of national heat and cold records on wunderground.com's extremes page, where all of this year's national heat records are updated. Weather records researcher Maximiliano Herrera is the primary source of these national weather records.

How much of the warming in recent decades is due to natural causes?
The El Niño/La Niña cycle causes cyclical changes in global temperatures that average out close to zero over the course of several decades. La Niña events bring a large amount of cold water to the surface in the equatorial Eastern Pacific, which cools global temperatures by up to 0.2°C. El Niño events have the opposite effect. During 2012, a weak La Niña event was present through March. Warming of the Eastern Pacific waters in the spring brought on neutral conditions, which lasted for the remainder of the year. The year 2012 was the warmest year on record when a La Niña event was present, surpassing the previous record set just the year before, in 2011. Global temperatures were 0.09°C (0.16°F) cooler than the record warmest year for the planet (2010), and 2012 would very likely have been the warmest on record had an El Niño event been present instead of a La Niña, as seen by looking at the year-to-date global temperature plot for 2012.


Figure 3. Departure from average of annual global temperatures between 1950 - 2012, classified by phase of the El Niño-Southern Oscillation (ENSO). The year 2012 was the warmest year on record when a La Niña event was present. ENSO is a natural episodic fluctuation in sea surface temperature (El Niño/La Niña) and the air pressure of the overlying atmosphere (Southern Oscillation) across the equatorial Pacific Ocean. Over a period of months to a few years, ENSO fluctuates between warmer-than-average ocean surface waters (El Niño) and cooler-than-average ocean surface waters (La Niña) in that region. Earth's warmest years tend to occur when an El Niño is present; cooler years occur when a La Niña is occurring. A La Niña (El Niño) year is defined here as occurring when the first three months of a calendar year meet the La Niña (El Niño) criteria as defined by NOAA's Climate Prediction Center. Image credit: National Climatic Data Center.

Correcting for natural causes to find the human contribution
We know that natural episodes of global warming or cooling in the distant past have been caused by changes in sunlight and volcanic dust. So, it is good to remove these natural causes of global temperature change over the past 34 years we have satellite data, to see what the human influence might have been during that time span. Through 2010, the three major research groups that maintain global surface temperature data sets (NCDC, GISS, and HadCRU) all show global temperatures have warmed by 0.16 - 0.17°C (0.28 - 0.30°F) per decade since satellite measurements began in 1979. The two satellite-based data sets of the lower atmosphere (maintained by UAH and RSS) give slightly less warming, about 0.14 - 0.15°C (.25 - .27°F) per decade (keep in mind that satellite measurements of the lower atmosphere temperature are affected much more strongly by volcanic eruptions and the El Niño phenomena than are surface-based measurements taken by weather stations.) A 2011 paper published by Grant Foster and Stefan Rahmstorf, Global temperature evolution 1979 - 2010, took these five major global temperature data sets and adjusted them to remove the influences of natural variations in sunlight, volcanic dust, and the El Niño/La Niña cycle. The researchers found that adjusting for these natural effects did not change the observed trend in global temperatures, which remained between 0.14 - 0.17°C (0.25 - 0.31°F) per decade in all five data sets. The warmest years since 1979 were 2010 and 2009 in all five adjusted data sets. The known natural causes of global warming have little to do with the observed increase in global temperatures over the past 34 years, and the vast majority of actively publishing climate scientists agree that human activity is the primary cause of increasing global temperatures in recent decades.


Figure 4. Departure from average of annual global temperatures between 1979 - 2010, adjusted to remove natural variations due to fluctuations in the El Niño-Southern Oscillation (ENSO) cycle, dust from volcanic eruptions, and changes in sunlight. The five most frequently-cited global temperature records are presented: surface temperature estimates by NASA's GISS, HadCRU from the UK, and NOAA's NCDC, and satellite-based lower-atmosphere estimates from Remote Sensing Systems, Inc. (RSS) and the University of Alabama Huntsville (UAH.) Image credit Global temperature evolution 1979- 2010 by Grant Foster and Stefan Rahmstorf, Environ. Res. Lett. 6, 2011, 044022 doi:10.1088/1748-9326/6/4/044022.


Video 1. Human emissions of heat-trapping gases like carbon dioxide have continued to warm the planet over the past 16 years. However, a persistent myth has emerged in the mainstream media challenging this. Denial of this fact may have been the favorite climate contrarian myth of 2012. Video courtesy of skepticalscience.com.

Top Ten Weather Lists for 2012

My Top Ten Global Weather Events of 2012

My Top Ten U.S. Weather Events of 2012.

NCDC's Top Ten Annual Weather/Climate Events

Wunderground's Angela Fritz's has a list of Top Climate Events of 2012.

A group of seventeen climate scientists and climate bloggers created a Climate Disruption: Critical 2012 Events and Stories list of 19 key climate change events that occurred in 2012.

TWC's Stu Ostro has his annual post showing his pick for top weather images of 2012.

Climate Central has a top-ten most striking images of 2012 post.

Jeff Masters

Climate Summaries Climate Change

Extreme jet stream causing record warmth in the east, record cold in the west

By: JeffMasters, 4:46 PM GMT on January 14, 2013

Los Angeles, California recorded its coldest temperature in 22 years on Sunday, and record daily lows fell across large portions of the Western U.S. over the weekend. But meanwhile, much of the Eastern U.S. basked in record-breaking warmth, with temperatures reaching the upper 60s in New York. What's going on? Well, the jet stream--the upper level river of strong winds that marks the boundary between cold, Arctic air to the north and warm, subtropical air to the south--has worked itself into a very extreme configuration. The jet is diving far to the south over the Western U.S., creating a U-shaped trough of low pressure that allows cold air to spill southwards out of Canada. The 34°F reading on Sunday morning in Los Angeles was the coldest temperature there since December 23, 1990. (The lowest temperature ever recorded in downtown Los Angeles was 28°F, most recently on January 4, 1949.) The -20°F observed at Grand Canyon, Arizona on Sunday morning tied for the coldest temperature measured there in 37 years of record keeping. At least three other stations in the West had their coldest January temperature on record over the weekend (January 12 - 13.) And, according to wunderground's weather historian Christopher C. Burt, Lakeview, Oregon hit -26°F on Sunday morning, beating their all-time record low of -24°F set in 1888. This is the first site of the 298 sites that he follows on our Extremes Page to tie or break its all-time cold record since Santa Fe, New Mexico did so on Feb. 3, 2011. Since 1997, only four of the 298 stations that he tracks have recorded all-time lows; 71 have recorded all-time highs.


Figure 1. All-time records for the month of January set so far in 2013, as cataloged by the wunderground Extremes Page. The page is showing that three stations have set new January low-temperature records (excluding a bogus one in Texas), and seventeen have set all-time January high temperature records.

Extreme January warmth in the East
To compensate for it's southwards bulge over the Western U.S., the jet stream is contorted into a sharp upside-down U-shaped ridge of high pressure over the Eastern U.S. This has allowed mild, subtropical air to flow northwards all the way to Canada, resulting in all-time records for January warmth to be tied or broken for at least eighteen sites over the past week. Notably, Mount Washington, NH (46°), Fayetteville NC (79°), and Bluefield, WV (72°) all tied or broke records for warmest January day over the weekend. In Michigan, the warmth was so unusual on Saturday morning that Traverse City, Michigan tied its record high temperature for January 12 at midnight, when the temperature had already risen to 50°.


Figure 2. The position of the jet stream is marked by where the strongest winds blow in the upper atmosphere. On January 14, 2013, the jet stream dove far to the south over the Western U.S., creating a U-shaped trough of low pressure that allowed cold air to spill southwards out of Canada. To compensate for it's southwards bulge over the Western U.S., the jet stream was contorted into a sharp upside-down U-shaped ridge of high pressure over the Eastern U.S. , allowing mild, subtropical air to flow northwards into New England and Eastern Canada. Image from wunderground's Jet Stream page.

Arctic sea ice loss: a potential contributor to extreme jet stream patterns
We've been seeing an increasing number of situations in fall and in winter in recent years where the jet stream has taken on the sort of extreme configuration that we are seeing today. Dr. Jennifer Francis of Rutgers has published research showing that Arctic sea ice loss may significantly affect the upper-level atmospheric circulation, slowing its winds and increasing its tendency to make contorted high-amplitude loops. High-amplitude loops in the upper level wind pattern (and associated jet stream) increases the probability of persistent weather patterns in the Northern Hemisphere, potentially leading to longer-duration cold spells, snow events, heat waves, flooding events, and drought conditions. Arctic sea ice hit an all-time low during 2012 and remains near record low levels, so it is possible that Arctic sea ice loss contributed to the current extreme jet stream configuration, and the past week's spate of extreme temperatures on both sides of the U.S.

Other wunderground blogs: The Climate Lottery, and Easing the Global Water Crisis
Lead Forecaster Guy Walton at TWC keeps diligent track of monthly U.S. temperature records, and posts a regular "Climate Lottery" analysis of monthly and annual rankings of U.S. temperatures. His first wunderground post on the subject, Climate Lottery-Mega Ball Ranking of 2012 is now up in our blog section.

Wunderground's Angela Fritz's blog has a guest post on the global water crisis from Wendy Pabich, author of Taking on Water: How One Water Expert Challenged Her Inner Hypocrite, Reduced Her Water Footprint (Without Sacrificing a Toasty Shower), and Found Nirvana. Wendy holds a Ph.D. in environmental engineering from the Parsons Water Resources Laboratory at MIT, and will be starting a "water challenge" on wunderground in the upcoming weeks to raise awareness of water usage, and to help us all lower our personal water usage.

Jeff Masters

Extreme Weather Heat Winter Weather Climate Change

Top Ten Global Weather Events of 2012

By: JeffMasters, 5:34 PM GMT on January 11, 2013

It was another year of incredible weather extremes globally during 2012. The year featured two of the most expensive weather disasters in world history--Hurricane Sandy and the Great U.S. Drought of 2012, which will both cost more than $50 billion. Thankfully, no disasters had a death toll in excess of 2,000, though the 1,901 people dead or missing due to Super Typhoon Bopha in the Philippines may rank as that nation's 2nd deadliest typhoon ever. Twenty-six weather disasters costing at least $1 billion occurred globally, according to insurance broker AON Benfield. Eleven billion-dollar weather disasters hit the U.S., a figure exceeded only by the fourteen such disasters in 2011. Nine billion-dollar weather disasters hit China, their highest total in a decade of record-keeping. I present for you, now, the top ten global weather stories of 2012, chosen for their meteorological significance and human and economic impact:



1) New Record Minimum for Arctic Sea Ice (September 16)
Sea ice extent in the Arctic fell to 3.41 million square kilometers on September 16, breaking the previous all-time low set in 2007 by 18%--despite the fact that 2012's Arctic weather was much cloudier and cooler than in 2007. Nearly half (49%) of the icecap was gone during 2012s minimum, compared to the average minimum for the years 1979 - 2000. This is an area approximately 43% of the size of the contiguous United States. And, for the fifth consecutive year--and fifth time in recorded history--ice-free navigation was possible in the Arctic along the coast of Canada (the Northwest Passage), and along the coast of Russia (the Northeast Passage or Northern Sea Route.) "We are now in uncharted territory," said NSIDC Director Mark Serreze. "While we've long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur. While lots of people talk about opening of the Northwest Passage through the Canadian Arctic islands and the Northern Sea Route along the Russian coast, twenty years from now from now in August you might be able to take a ship right across the Arctic Ocean." Arctic sea ice is an important component of the global climate system. The polar ice caps help to regulate global temperature by reflecting sunlight back into space. White snow and ice at the poles reflects sunlight, but dark ocean absorbs it. Replacing bright sea ice with dark ocean is a recipe for more and faster global warming. The fall air temperature over the Arctic has increased by 4 - 6°F in the past decade, and we could already be seeing the impacts of this warming in the mid-latitudes, by an increase in extreme weather events. Another non-trivial impact of the absence of sea ice is that is causes increased melting in Greenland, contributing to sea level rise.


Figure 1. A sunny, slushy day near the North Pole on September 1, 2012. Webcam image courtesy of the North Pole Environmental Observatory. It won't be many years before Santa's workshop needs pontoons in the summer to stay afloat.

2) Agricultural Drought in the U.S., Europe, and Asia (Summer)
Drought is civilization's great enemy, and the most dangerous threat from global warming. Drought impacts the two things we need to live--food and water. When the rains stop and the soil dries up, cities die and civilizations collapse, as people abandon lands no longer able to supply them with the food and water they need to live. In a harbinger of things to come, severe droughts affected important agricultural regions across the globe during summer 2012, including eastern Russia, Ukraine, Kazakhstan, and central North America. Wheat, corn, and soybean crops were among those heavily impacted; global food prices rose by 10 percent during July. While it will be several months before the costs of America's worst drought since the 1930s Dust Bowl are known, the 2012 drought is expected to cut America's GDP by 0.5 - 1 percentage points, said Deutsche Bank Securities. Since the U.S. GDP is approximately $15 trillion, the drought of 2012 represents a $75 - $150 billion hit to the U.S. economy. This is in the same range as the estimate of $77 billion in costs for the drought, made by Purdue University economist Chris Hurt in August, and the Great U.S. Drought of 2012 is going to be one of the top-five most expensive weather disasters in world history.


Figure 2. Corn in Colby, Kansas withers in the Great Drought of 2012 on May 27. Image credit: Wunderphotographer treeman.

3) Superstorm Sandy (October 29)
Hurricane Sandy was the most powerful and second most destructive Atlantic hurricane in recorded history. Ten hours before landfall, at 9:30 am EDT October 29, the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules--the highest value for any Atlantic hurricane since at least 1969, and equivalent to more than five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been larger. Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee--an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lake Shore, and toppled power lines in Nova Scotia, Canada--locations 1200 miles apart! Sandy made landfall near Atlantic City, NJ on October 29, with sustained winds of 80 mph and a central minimum pressure of 946 mb--the lowest pressure on record along the Northeast coast. The Battery, in New York City Harbor, had an observed water level of 13.88 feet, besting the previous record set by Hurricane Donna in 1960 by 3 feet. Sandy's catastrophic storm surge was responsible for the majority of the 131 deaths and $62 billion in damage in the U.S. Sandy also brought torrential rainfall in excess of 12 inches to the mid-Atlantic, and blizzard conditions to the central and southern Appalachians. Sandy's late-season show of unprecedented strength, unusual track, and exceptionally damaging storm surge were made more likely due to climate change, and the storm helped bring more awareness and debate about the threat of climate change to the U.S. than any event since Hurricane Katrina in 2005.


Figure 3. Hurricane Sandy at 10:10 am EDT October 28, 2012. Image credit: NASA/GSFC.

4) Greenland Ice Sheet melt and Glacier Calving (July)
Measurements from three satellites showed that on July 8, about 40 percent of the Greenland ice sheet had undergone thawing at or near the surface. But during four consecutive days July 11 - 14, temperatures rose above freezing at the top of the Greenland Ice Sheet, which is 10,551 feet (3216 meters) above sea level and 415 miles (670 km) north of the Arctic Circle. Melting of the ice sheet dramatically accelerated, and an estimated 97 percent of the ice sheet surface had thawed by July 12. This was the greatest melt since 1889, according to ice core records. On July 16, an iceberg twice the size of Manhattan calved from the Petermann Glacier in Northeast Greenland. This was the second huge ice island to calve from the glacier since 2010. The glacier's margins have now retreated to the farthest point in the last 150 years. The record melt in Greenland caused the highest loss of ice mass observed in the satellite era, and melting from Greenland is now thought to cause about 0.7 mm/year of global sea level rise, which is about 20 - 25% of the global total.


Figure 4. The massive 46 square-mile iceberg two times the size of Manhattan that calved from Greenland's Petermann Glacier on July 16, 2012, as seen on July 21, 2012, using MODIS satellite imagery. Image credit: NASA.

5) Super Typhoon Bopha (December 3 - 4)
The deadliest weather disaster of 2012 was Super Typhoon Bopha. Bopha was the strongest typhoon ever hit the southern Philippine island of Mindanao, making landfall as a Category 5 super typhoon with winds of 160 mph (260 km/h) on December 3. Bopha made two additional landfalls in the Philippines, on central Visayas and on Palawan, on December 4. The typhoon left 1901 people dead or missing, mostly on the island of Mindanao. If the missing people are presumed dead, this total would make Bopha the 2nd deadliest typhoon in Philippine history. Bopha affected over 5.4 million people and left over 700,000 people homeless. With damages estimated at $1.04 billion, Bopha is the most costly typhoon ever to hit the Philippines. The previous record was the $600 million price tag of 2009's Typhoon Parma.


Figure 5. December 7, 2012: rescuers and residents look for missing victims amongst toppled tree trunks and coconut shells after flash floods caused by Super Typhoon Bopha hit Compostela Valley on Mindanao Island in the Philippines on December 3 - 4, 2012. (AP Photo/Jay Morales, Malacanang Photo Bureau, HO)

6) Northern Hemisphere Warmth (throughout 2012)
Land areas in the Northern Hemisphere reached record warm monthly values for four consecutive months (April - July). Much of the unusual warmth occurred in North America; Canada was 3rd warmest on record for the period January- September, and the United States had its warmest year on record. Many European countries and Russia had record to near-record warm summer temperatures in 2012.


Figure 6. This young lady chose to cool her heels in the Fox River on June 28, 2012, as the temperature was topping 102 degrees in Carpentersville, IL imag credit: wunderphotographer pjpix.

7) Eurasian Continent Cold Wave (January 24 - February 17)
Europe's worst cold snap in at least 26 years hit central and eastern Europe hard during a 3-week period in late January and the first half of February. The 824 deaths being blamed on the cold wave made it 2012's second deadliest weather disaster. Parts of the Danube River froze over for the first time in 25 years, and Northeast China through eastern Inner Mongolia recorded extremely cold minimum temperatures ranging between -30°C to -40°C.


Figure 7. Snow falls in Trogir, Croatia on February 3, 2012. Image credit: wunderphotographer antoniomise.

8) China Floods (July 21 - 22)
Torrential downpours on July 21 - 22 affected Beijing, Tianjin, and Hebei, with several stations recording their highest daily precipitation on record. Mentougou recorded an impressive 305.2 mm (12 inches) of precipitation in one day. The floods killed 129 people and did $4.8 billion in damage, one of a record nine billion-dollar weather disasters to affect China in 2012.


Figure 8. A Chinese man uses a signboard to signal motorists driving through flooded street following a heavy rain in Beijing Saturday, July 21, 2012. China's government says these were the heaviest rains to hit Beijing in six decades. The torrential downpour left low-lying streets flooded and knocked down trees. (AP Photo)

9) Pakistan Floods (August 21 - September 30)
Torrential monsoon rains caused deadly floods in Pakistan, with Balochistan, Punjab, and Sindh provinces the hardest hit. Over 5 million people and over 400,000 hectares of crops were affected by the floods, with more than 460,000 houses and infrastructures damaged or destroyed. The death toll of 455 made it Earth's 3rd deadliest weather-related disaster of 2012.


Figure 9. A driver makes his way on a street flooded from heavy rain in Peshawar, Pakistan, Tuesday, Aug. 28, 2012. (AP Photo/Mohammad Sajjad)

10) African Floods (July - October)
Heavy rains in Nigeria killed at least 431, making it Earth's 4th deadliest weather disaster of 2012. Over 3 million people were affected by flooding across 15 countries in Africa, most notably Nigeria, Niger, Senegal, and Chad. The floods destroyed farmlands, homes, and schools, and caused outbreaks of cholera and other diseases.

Other Top Ten Weather Lists of 2012
My Top Ten U.S. Weather Events of 2012.

Wunderground's Angela Fritz's has a list of Top Climate Events of 2012.

A group of seventeen climate scientists and climate bloggers created a Climate Disruption: Critical 2012 Events and Stories list of 19 key climate change events that occurred in 2012.

TWC's Stu Ostro has his annual post showing his pick for top weather images of 2012.

Climate Central has a top-ten most striking images of 2012 post.

Have a great weekend, everyone!

Jeff Masters

Climate Summaries Extreme Weather

A record 199 days without a tornado death; 1st tornado of 2013 hits Louisiana

By: JeffMasters, 4:10 PM GMT on January 10, 2013

The U.S. has set a weather record of the sort we like to see: the longest continuous stretch without a tornado death. We've had 199 days without a tornado fatality, beating the record of 197 straight days that ended on February 28, 1987. The last U.S. tornado death was at Venus in Highlands County, Florida, from an EF-0 tornado associated with Tropical Storm Debby on June 24, 2012. After a horrific 2011 that saw 553 Americans die in tornadoes--the 2nd highest total since 1950--the 2012 tornado season was not far from average for deaths, according to NOAA's Storm Prediction Center. The 2012 tornado death toll was 68, ranking 25th highest since 1950. The average yearly toll between 1950 - 2011 was 91. According to SPC, the total number of tornadoes during 2012 was just 936. This is the first time since 2002 that fewer than 1000 tornadoes have been recorded. The reason for the low tornado total in 2012 was the massive drought that gripped much of Tornado Alley. It's tough to get tornadoes when you're experiencing near-record drought conditions and very few thunderstorms.


Figure 1. June 24, 2012: A tornado spawned by Tropical Storm Debbie crosses Lake Winterset in Winter Haven, Florida. Another tornado from Debbie on this day caused the last tornado death in the U.S., at Venus in Highlands County, Florida. Image credit: wunderphotographer whgator3.


Figure 2. The total number of U.S. tornadoes stronger than EF-0 from 1950 - 2012 does not show a significant long-term trend. However, this database is not very reliable, and we cannot use it to make judgements about how tornadoes may be changing in the long term. Data taken from NOAA's Storm Prediction Center (SPC). Since not all tornadoes from 2012 have been given an EF scale rating yet, the numbers from 2012 are estimated by assuming that the same proportion of EF-0 tornadoes that existed in 2011 also occurred in 2012.

First U.S. tornado of 2013 hits Louisiana
A powerful low pressure system centered over Texas that has dumped over 5" of rain over Southeast Texas and 10" over portions of Louisiana has generated the first U.S. tornado of 2013. The tornado touched down in Plaquemine, Louisiana at 8:35 am CST this morning, when a squall line of severe thunderstorms moved through. Light to moderate roof damage was reported at an industrial plant on Highway 405, about 80 miles west-northwest of New Orleans. NOAA's Storm Prediction Center has portions of Southeast Louisiana, Southern Mississippi, and Southern Alabama in their "Slight Risk" region for severe weather and tornadoes, so hopefully our record streak without a tornado death will not come to an end today.


Figure 3. Radar-estimated precipitation from the past three days from the Lake Charles radar. Over 10" of rain (dark pink colors) is estimated to have fallen over South Central Louisiana.

Earth's extreme weather: no big deal, compared to Venus
Our colleagues at TWC are airing a new series that starts tonight (Thursday) at 9pm EST/8pm CST, called "Deadliest Space Weather." We've put the trailer for tonight's episode on Venus up on the wunderground video section. As I highlighted in my book review of Dr. James Hansen's must-read book, Storms of My Grandchildren, Dr. Hansen argues that Earth's climate may eventually wind up like Venus', with a run-away greenhouse effect: "After the ice is gone, would Earth proceed to the Venus syndrome, a runaway greenhouse effect that would destroy all life on the planet, perhaps permanently? While that is difficult to say based on present information, I've come to conclude that if we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty." In tonight's episode of "Deadliest Space Weather", astronomers and planetary scientists will reveal why the climate of Venus went so horribly wrong, why a similar climate may one day descend on the Earth--and what will happen when it gets here.

Jeff Masters

Tornado

2012: warmest and 2nd most extreme year in U.S. history

By: JeffMasters, 9:01 PM GMT on January 08, 2013

The contiguous U.S. smashed its record for hottest year on record in 2012, according to NOAA's National Climatic Data Center (NCDC). The annual U.S. average temperature was 3.3°F above the 20th century average, and was an astonishing 1.0°F above the previous record, set in 1998. It is extremely rare for an area the size of the U.S. to break an annual average temperature record by such a large margin. Nineteen states, stretching from Utah to Massachusetts, had annual temperatures which were record warm. An additional 26 states had a top-ten warmest year. Only Georgia (11th warmest year), Oregon (12th warmest), and Washington (30th warmest) had annual temperatures that were not among the ten warmest in their respective period of records. As wunderground's weather historian Christopher C. Burt reported, of the approximately 5,500 U.S. stations in the NCDC database, 362 recorded their all-time highest temperature during 2012, and none recorded an all-time coldest temperature. This was the most since the infamous Dust Bowl summer of 1936. Approximately 7% of the contiguous U.S. experienced an all-time hottest day during 2012, and every state in the contiguous U.S. except Washington had at least one location experience its warmest year on record. One notable warmest year record occurred in Central Park, in New York City, which has a period of record dating back 136 years.

The 2012 weather was also very dry, and the year ranked as the 15th driest year on record for the contiguous U.S. Wyoming and Nebraska had their driest year on record, and eight other states had top-ten driest years. The area of the contiguous U.S. experiencing moderate-to-exceptional drought peaked at 61.8% during July. This was the largest monthly drought footprint since the Dust Bowl year of 1939.


Figure 1. Historical temperature ranking for U.S. states in 2012. Nineteen states had their warmest year on record, and an additional 26 were top-ten warm. Image credit: National Climatic Data Center (NCDC).


Figure 2. Temperatures for the contiguous U.S. in 2012, compared to the previous record warmest and coldest years in U.S. history. The annual U.S. average temperature was 3.3°F above the 20th century average, and was an astonishing 1.0°F above the previous record, set in 1998. It is extremely rare for an area the size of the U.S. to break an annual average temperature record by such a large margin. Image credit: NOAA/NCDC.

Second most extreme year on record
The year 2012 was the second most extreme on record in the contiguous U.S., according to NOAA's U.S. Climate Extremes Index (CEI), which tracks the percentage area of the contiguous U.S. experiencing top-10% and bottom-10% extremes in temperature, precipitation, and drought, plus winds from landfalling tropical storms and hurricanes. The CEI was 39% in 2012, approximately double the average of 20%. The only year that was more extreme since CEI record keeping began in 1910 was 1998--the United States' previous warmest year on record. Since Hurricane Sandy was not considered a hurricane when it came ashore, that storm did not contribute to the 2012 CEI. If one plots up the CEI without using the tropical storm and hurricane indicator, 2012 is the most extreme year on record, beating out 1998, 46% to 42%. During 2012, a record 87% of the contiguous U.S. had maximum temperatures that were in the warmest 10% historically, crushing the previous record of 62% set in 1934; 74% of the U.S. of the U.S. had warm minimum temperatures in the top 10% in 2012 (2nd highest on record.) The percentage area of the U.S. experiencing top-10% drought conditions was 34%, which was the 4th greatest since 1910. Only droughts in the Dust Bowl year of 1934, and during 1954 and 1956, were more extreme, averaged over the entire year. Heavy 1-day downpours were near average in 2012, though, with 9% of nation experiencing a top-10% extreme, compared to the average of 10%.


Figure 3. NOAA's U.S. Climate Extremes Index (CEI) pegged 2012 as the second most extreme year on record, with 39% of the contiguous U.S. experiencing top-10% extreme weather. This is approximately double the average of 20% (heavy black line.)

Jeff Masters

Climate Summaries Extreme Weather

Historic heat wave brings Australia its hottest average temperature on record

By: JeffMasters, 2:27 PM GMT on January 08, 2013

It's been a summer like no other in the history of Australia, where a sprawling heat wave of historical proportions is entering its second week. Monday, January 7, was the hottest day in Australian history, averaged over the entire country, according to the Australian Bureau of Meteorology. The high temperature averaged over Australia was 105°F (40.3°C), eclipsing the previous record of 104°F (40.2°C) set on 21 December 1972. Never before in 103 years of record keeping has a heat wave this intense, wide-spread, and long-lasting affected Australia. The nation's average high temperature exceeded 102°F (39°C) for five consecutive days January 2 - 6, 2013--the first time that has happened since record keeping began in 1910. Monday's temperatures extended that string by another day, to six. To put this remarkable streak in perspective, the previous record of four consecutive days with a national average high temperature in excess of 102°F (39°C) has occurred once only (1973), and only two other years have had three such days in a row--1972 and 2002 (thanks go to climate blogger Greg Laden for these stats.) Another brutally hot day is in store for Wednesday, as the high pressure region responsible for the heat wave, centered just south of the coast, will bring clear skies and a northerly flow of air over most of the country. A slight cool down will occur later in the week, as the high weakens and slides to the east of Australia. The western coast of Australia may see cloud cover and rain from Tropical Cyclone Narelle this weekend, but the rest of the country will see very little in the way of cloud cover or rain during the coming week.


Figure 1. Aerial view of fire at Copping/Forcett, Tasmania, at around 4pm on 4 Jan 2013, taken from an airplane leaving Hobart Airport. Image credit: Wikipedia.

As discussed by wunderground's weather historian Christopher C. Burt in his Monday post, Australia's extreme heat helped fuel wild fires in southeastern Tasmania that burned to the ground at least 100 homes last Friday and Saturday. The temperature peaked in the state capital of Hobart at 41.8°C (107.2°F) on Friday, the hottest temperature on record for the city, and tied for the 2nd hottest temperature ever recorded in Tasmania (records go back to 1882). The 2013 Australian heat wave extends a period of unusual warmth for the country. The last four months of 2012 were the hottest such period on record, with an average Australian maximum temperature +1.61°C, just beating the previous record of 1.60°C set in 2002. The current heat wave has not yet set a record for all-time hottest temperature in Australian history, which remains the 50.7°C (123.3°F) reading on 2 January 1960 at Oodnadatta, South Australia.


Figure 2. Departure of high temperature from average (using a base period of 1961 - 1990) for the first six days of 2013. A large area of Australia has had high temperatures more than 6°C (11°F) higher than average. Image credit: Australian Bureau of Meteorology.

Jeff Masters

Heat

Hurricane Isaac's legacy: wetland destruction, and a test of the New Orleans levees

By: JeffMasters, 5:05 PM GMT on January 07, 2013

The hurricane season of 2012 will rightfully be remembered for the legacy left behind by Hurricane Sandy. But in Louisiana, the other hurricane to affect the U.S. in 2012--Hurricane Isaac--left a legacy of its own. Isaac hit Louisiana as a Category 1 hurricane with 80 mph winds on August 28, but the storm's massive wind field brought a storm surge characteristic of a Category 2 hurricane to the coast. A storm surge of 11.1 feet was measured at Shell Beach, LA and higher surges were reported in portions of Louisiana. The surge levels experienced along portions of the New Orleans levee system were similar in magnitude to the surge of Hurricane Katrina in 2005. Fortunately, the new $14.5 billion upgrade to the New Orleans levee system kept the city dry, and we can now be confident that the city will stay protected from Category 2-level storm surges. The new levee system has yet to be tested against a full Category 3-level storm surge, the maximum it is designed to handle.


Figure 1. Hurricane Isaac lit up by moonlight as it spins towards the city of New Orleans, LA, on August 26, 2012. The Suomi National Polar-orbiting Partnership (NPP) satellite captured these images with its Visible Infrared Imaging Radiometer Suite (VIIRS). The "day-night band" of VIIRS detects light in a range of wavelengths from green to near-infrared and uses light intensification to enable the detection of dim signals. Image Credit: NASA/NOAA, Earth Observatory.

Environmental impacts of Isaac
One major long-term environmental impact of Isaac will be the erosion and destruction of wetlands along the Southern Louisiana coast. A 2011 study by the USGS found that four hurricanes in the past seven years--Katrina, Rita, Gustav, and Ike--have together destroyed about 250 square miles of Louisiana marshland--an area 20% the size of Rhode Island. Researchers have yet to quantify how great Isaac's impact was on Louisiana's wetlands, but given Isaac's large size, large storm surge, and the extended battering it gave the coast, I expect 2012 will be one of the state's highest years on record for wetland loss. Over the past 25 years, Louisiana has lost an average of 17 square miles per year of wetlands, and I expect Louisiana lost 30 - 70 square miles of wetlands in 2012, primarily due to Isaac. As I explain in my detailed article on Storm Surge Reduction by Wetlands, wetlands can help significantly reduce the storm surge from a hurricane, though the degree of protection wetlands provide from storm surges is extremely complicated and is largely unknown. The general rule of thumb is that each 2.7 miles of marsh reduces the storm surge by one foot, though wetlands will provide almost no protection from a slow-moving storm like Isaac, which had enough time to completely inundate the coast, despite the presence of wetlands. Louisiana's wetlands have other huge benefits besides hurricane protection, though--they filter out nutrients that would contribute to the huge Gulf of Mexico dead zone, they support 25% of the nation's total commercial fishing haul, and provide storm protection to five of the nation's largest ports.


Figure 2. Hurricane Isaac inundated large areas of Southeastern Louisiana due to storm surge levels in excess of 10'. Image credit: USGS.

One way in which Isaac may have helped the marshlands of Louisiana and Mississippi, though, is that the storm drowned tens of thousands of Nutria, the large semi-aquatic South American rodents released in Louisiana and Mississippi in the 1930s by fur trappers looking for new stock. Nutria can severely reduce overall wetland biomass, and lead to the conversion of wetland to open water. Populations were kept in check as long as fur prices were high, but a fur price collapse in the 1980s led to a nutria population explosion into the millions. The Louisiana Department of Wildlife and Fisheries emphasizes that without effective, sustainable nutria population control, coastal wetland restoration projects will be greatly hindered. The Louisiana's 2012 Coastal Master Plan, unanimously approved by the Louisiana State Legislature in May 2012, called for 109 projects costing $50 billion over 50 years to use a combination of restoration, nonstructural, and targeted structural measures to provide increased flood protection. Louisiana needs to build a series of engineered structures called diversions along the lower Mississippi River in order to restore river sediment to Louisiana's marshlands, said a report co-authored by 22 prominent scientists and engineers in April 2012.

Jeff Masters

Superstorm Sandy and the importance of polar orbiting satellites in forecasting

By: JeffMasters, 8:19 PM GMT on January 03, 2013

On the 23rd of October, the 18th named storm of the 2012 Atlantic hurricane season, Tropical Storm Sandy, was born in the Central Caribbean. As is common for late-season storms in the Caribbean, Sandy moved northwards across Cuba. The official forecasts from the National Hurricane Center issued on October 23 called for Sandy to turn to the northeast after crossing Cuba, and head into the Central Atlantic. This forecast was based on the output from five of our top six computer models, which all predicted that an upper-level low pressure system in the Central Atlantic would be strong enough to pull Sandy northeastwards. However, the global weather forecast model run by the European Center for Medium-Range Weather Forecasts (ECMWF) showed a disturbing possibility: the upper-level low pressure system in the Central Atlantic would not be strong enough to turn Sandy to the northeast. The hurricane would instead get caught up in the flow associated with a trough of low pressure approaching the U.S. East Coast, and Sandy would get slung into New York or New Jersey on October 29. While the ECMWF model was the best performing model for tracking Atlantic hurricanes in both 2010 and 2011, and had done very well again so far in 2012, the American GFS model had outperformed the ECMWF model several times during the 2012 season. NHC elected to discount the ECMWF forecast for Sandy as an outlier, and went with the forecast from the GFS and other models. By October 25, it was clear that the ECMWF model had the right idea all along. More models were now showing the turn towards New York, and the official NHC forecast now called for Sandy to make landfall in New York or New Jersey on October 29. The ECMWF model's early forecast of a track for Sandy into the Northeast was critical for allowing additional time for residents to prepare for arrival of the devastating storm. So what enabled the ECMWF model to make such an excellent forecast for Sandy, six days in advance?


Figure 1. This image uses the model output from the ECMWF experiment, showing where Sandy was predicted to be located five-days out with the normal satellite data inputs into the model (left) and without any polar-orbiting satellite data (right). Both position and intensity forecasts were affected--Sandy stays out to sea without the polar-orbiting satellite data, and the closer isobar lines encircling the storm also imply a more organized and stronger system. Image credit: NOAA.

Polar satellite data: a key to ECMWF model success
The ECWMF has a very sophisticated technique called "4-D Var" for gathering all the current weather data over the Earth and putting the data on a 3-dimensional grid that is then used as the initial "reality" of the current weather for the model to use for its forecast. The old expression, "garbage in, garbage out" is a truism for weather forecast models. If you don't properly characterize the initial state of the atmosphere, the errors you start off with will grow and give a lower-quality forecast. Data from geostationary satellites, which sit continuously at one spot above the globe, are easy to assimilate, and all the models use this data. However, the ECMWF model's superior technique used to assimilate the initial data allows inclusion of data from a large number of polar-orbiting satellites, which the other models cannot do as well. Polar-orbiting satellites orbit Earth at an altitude of 540 miles twice per day, circling from pole to pole. Their data is difficult to use, since the it is only available twice per day at each spot on the Earth, and the time of availability is different for each location. According to an email I received from Jean-Noël Thépaut, the chief of the Data Division of the Research Department at the European Center for Medium-Range Weather Forecasts, the ECMWF model uses data from at least fourteen polar orbiting satellites: N-15, N-19, N-19, N-17 (ozone SBUV instrument only), Metop-A, AQUA, NPP (ATMS instrument only), AURA (ozone OMI data only), F-17, TRMM (TMI data), COSMIC, GRACE-A, TERRASAR, and the GPSRO data on top of METOP-GRAS. The data of most importance is the data collected in the infrared and microwave wavelengths, as well as atmospheric density data obtained via GPS radio occultation (as a polar orbiting satellite goes over the horizon, the GPS signals from the satellite get bent by Earth's atmosphere, with the amount of bending proportional to the density of the atmosphere. This GPS Radio Occultation data is gathered from eight polar orbiting satellites, and fed into both the ECMWF and GFS models.) You can find a nice summary of the impacts of polar orbiting satellite data on weather prediction models at this link.)


Figure 2. Forecast track error for four of our top models used to predict Hurricane Sandy, for their runs that began at 00Z October 25, 2012. By this time, the GFDL model had joined the ECMWF in predicting that Sandy would make landfall in Southern New Jersey in five days. The GFS and HWRF models made good 1 - 3 day forecasts, but failed to anticipate Sandy's north-northwestward turn towards the U.S. coast. Image credit: Morris Bender, NOAA/GFDL.

As originally reported by the Washington Post's Capital Weather Gang, then confirmed in a NOAA press release, a study done by ECMWF research scientist Tony McNally found that if the ECMWF model did not have all of the data from the fourteen polar orbiting satellites, the five-day forecast of the model for Hurricane Sandy would have shown Sandy missing the Northeast U.S. This brings up a concern, since the U.S. polar orbiting satellite program is behind schedule. As explained by Andrew Freedman of Climate Central, the program is plagued by mismanagement, billions in cost overruns, and technical development challenges. The next polar orbiting satellite is not scheduled to be launched until 2017, and one or more of the existing polar orbiting satellites are expected to fail before then. This will result in a degradation of our ability to observe and predict the weather, and may result in poorer forecasts for storms like Hurricane Sandy. Given that the ECMWF model used data from fourteen polar orbiting satellites, the failure of just one satellite may not have made a significant difference in its forecast for Sandy. But if we lose several of these key satellites by 2017, our hurricane forecasts in 2017 may be worse than they were in 2012. To figure out how to cope with the loss of satellite-derived data, NOAA is conducting a Gap Risk Study that seeks ideas from researchers and the public on how NOAA can preserve the quality of its weather model forecasts in the event of the failure of one or more polar orbiting satellites in the coming years.


Figure 3. A tanker rests on the southern shore after being swept onto land by a storm surge due to Superstorm Sandy, Friday, Nov. 2, 2012, in the Staten Island borough of New York. (AP Photo/ John Minchillo)

Links
Eric Berger of the Houston Chronicle has an interview with Jean-Noël Thépaut, chief of the Data Division of the Research Department at the European Center for Medium-Range Weather Forecasts, on why the European model did so well with Hurricane Sandy.

Jeff Masters

Hurricane Politics


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™

About

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