Category 6™

Historic Unseasonable Flood Begins on Mississippi River; 928 mb Low Hits Iceland

By: Jeff Masters , 5:13 PM GMT on December 30, 2015

A historic and unseasonable flood has begun on the Mississippi River and its tributaries, thanks to heavy rains that fell from Oklahoma to the Ohio Valley during Christmas week. Never before has water this high been observed in winter along the levee system of the river. The Father of Waters began over-topping its levees just north of West Alton, Missouri (population 500) on Tuesday, forcing evacuations. West Alton lies at the confluence of the Missouri and Mississippi Rivers, about 7 miles upriver from St. Louis. The river is still rising at West Alton, and is expected to crest on Thursday morning at the second highest level ever recorded, about 5' below the disastrous flood of 1993. On Friday, the massive Mississippi River flood crest will reach St. Louis, bringing the second highest waters levels ever recorded there (flood records extend way back to 1785 in St. Louis.) The three river gauges downstream from St. Louis--at Chester, Cape Girardeau, and Thebes--are expected to see their highest water highest levels ever recorded on Friday and Saturday. The latest flood forecasts for the Mississippi River issued Tuesday evening by NWS River Forecast Center predicted that Thebes would be the last location to see an all-time record crest in this flood; below Thebes, flood crests between the 2nd and 4th highest on record are expected along most of the Mississippi and the lower portions of two main tributaries, the Ohio and Arkansas Rivers. As with weather forecasts, the margin of uncertainty in river-crest predictions increases over longer time periods. According to a Wednesday morning summary by TWC's Jon Erdman, the following flooding and flood impacts can be expected farther down river:

• Memphis: Crest late next week higher than 1997 and 1973 floods, but well below 2011 and 1937 floods.
• Vicksburg, Mississippi: Crest in mid-January expected to exceed 1973 flood, but well below 2011 and 1927 floods. Some flooding of city streets and businesses possible.
• Natchez, Mississippi: Crest around MLK holiday may top 1937 flood, but should remain below 2011 record flood. Flooding of Ft. Adams likely.
• Baton Rouge, Louisiana: Crest during MLK week comparable or just below May 2011 flood possible. Areas outside of levee protection may flood. Shipping and industrial activities may be significantly impacted.


Figure 1. The Mississippi River downstream of St. Louis at Thebes was at major flood stage on Wednesday morning, and was forecast to crest on Friday at the highest level ever observed. Flood records at this location extend back to 1844. Image credit: NOAA/AHPS.

On January 20, the flood crest is expected to arrive in New Orleans, bringing the Mississippi River to its 17-foot flood stage in the city, just 3 feet below the tops of the levees. In past years, though, when the river has been forecast to rise to 17 feet in the city, the Army Corps of Engineers has opened up the Bonnet Carré Spillway in St. Charles Parish, which diverts water into Lake Pontchartrain and keeps the river from reaching flood stage in New Orleans. The Corps may also be forced to open the Morganza Floodway in Pointe Coupee Parish, which would divert water down the Atchafalaya River. Opening this spillway has a considerably higher cost than opening the Bonnet Carré Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Floodway. The Corps also has the option of increasing the flow of Mississippi River water into the Atchafalaya at the Old River Control Structure in Concordia Parish. Operating the Old River Control Structure in this way, though, puts stress on the structure, as I explained in my 2011 blog post, America's Achilles' heel: the Mississippi River's Old River Control Structure. The Tuesday evening forecast from the NWS River Forecast Center predicted that the Mississippi River would crest at Red River Landing, where the Old River Control Structure is located, on January 19. The predicted crest of 62.5' is just 0.9' below the all-time record crest of 63.39' set on May 18, 2011. A water level this high has a good chance of forcing the Army Corps to open the Morganza Floodway in order to relieve pressure on the Old River Control Structure. Both the Bonnet Carré Spillway and Morganza Floodway were opened in May 2011, when the highest flood crests ever observed on the Lower Mississippi arrived. This flood cost approximately $3 billion; $1 billion was required just to repair the damage done to the levee system and various other components of the flood control system damaged by the flood, according to Charles Camillo's book, Divine Providence: The 2011 Flood in the Mississippi River and Tributaries Project. I expect the damage from the December 2015 - January 2016 Mississippi River flood will run into the hundreds of millions. According to a Wednesday news story in The Advocate, the Army Corps will make a decision by January 9 on whether or not to open the Bonnet Carré Spillway. The last time the spillway was opened in January was back in 1937, its first year of operation. In a Wednesday morning Press Release, the Army Corps of Engineers indicated that they are mobilizing people, barges and operational equipment to open a third floodway on the Mississippi River near its confluence with the Ohio River--the Birds Point - New Madrid floodway. Opening up this floodway would help relieve pressure on the levees near Cairo, Illinois, something the Corps was forced to do in May 2011. However, the Corps said that they do not anticipate operating the floodway during the current flood, if current flood height predictions hold.


Figure 2. Existing flood stage on December 28, 2015 (inner colored square) and predicted maximum flood stage (outer colored square region around the inner colored square) for the Lower Mississippi River and two tributaries (the Arkansas and Ohio Rivers) near where they join the Mississippi. I've added numerical ranking on the right side of the squares to indicate where a top-ten flood crest in recorded history is expected. Two gauges are expecting their highest floods on record (Cape Girardeau and Thebes), and most of the Lower Mississippi is expecting a top-five highest flood crest on record. Where the Ohio River joins the Mississippi at Cairo, Illinois, the Ohio River is forecast to crest on January 5 at the third highest level on record; downstream from Little Rock, Arkansas, the Arkansas River is predicted to crest on Friday at the third highest level on record near its confluence with the Mississippi. Image credit: NWS River Forecast Center.

Massive 928 mb storm pummels Iceland and the UK
A massive North Atlantic low pressure system dubbed "Frank" bombed to a central pressure of 928 mb on Wednesday morning and moved over Iceland, bringing heavy rains to Iceland and the UK and hurricane-force winds to the ocean waters between. According to Weather Underground's weather historian Christopher C. Burt's 2011 post, World and U.S. Lowest Barometric Pressure Records, the storm missed setting a lowest pressure for Iceland; the lowest pressure measured on the island is probably the 923.6 mb reading on December 2, 1929. Chris also notes that there are two storms in the North Atlantic that likely had a minimum pressure below 920 mb:

1) Storm of January 10, 1993 deepened to a central pressure of 912-915 mb (26.93”-27.02”) between Iceland and Scotland near 62°N, 15°W

2) Storm of December 15-16, 1986 deepened to at least 916 mb southeast of Greenland near 62°N, 32°W. A ship in the vicinity actually made a measurement of 920.2 mb on December 15th while still some distance from the center of the storm. The British Meteorological Office assessed the central pressure of the storm at this time as being 916 mb (27.05”), but the West German meteorological service proposed a pressure possibly as low as 912-913 mb (see Stephen Burt article in Weather magazine Vol. 42 pp. 53-56, February 1987).

Some links to more info on Frank, courtesy of wunderground member barbamz:

Extreme Weather Causes Damage in East Fjords
Iceland Review, By Vala Hafstad Nature & Travel about 2 hours ago
The severe weather in the East Fjords is among the worst residents have ever experienced, RUV reports. The situation is the worst in Eskifjordur, where a high sea level land hurricane-force winds have threatened the marina. Part of the dock came loose, but rescue workers managed to fasten it. The surf has inundated all docks and the whole harbor area. Roof sheets have blown off several houses. There was high tide at 5:30 am, but since then, water levels have subsided somewhat. Boats that came loose in the marina were successfully tied down. Basements have flooded and tidal waves have reached cabins, never before affected by sea water. Some homes are without power...

VIDEO: "Absolutely crazy" storm in East Iceland
Iceland Monitor | Wed 30 Dec 2015 | 9.56 GMT

BBC Live: Storm Frank hits UK

Guardian: Storm Frank: further floods expected as gales and rain batter British Isles - live

BBC live report especially for Cumbria.

Near the southern coast of Ireland yesterday:





Figure 3. Surface analysis from 06 UTC December 30, 2015 showing intense Winter Storm Frank with a central pressure of 928 mb over Iceland. Image credit: NOAA Ocean Prediction Center.

Incredibly warm air flowing to the North Pole
The counter-clockwise flow of air in advance of Wednesday's Icelandic low is following an unusually contorted kink in the jet stream and pumping relatively warm air all the way to the North Pole, where temperatures near freezing may be occurring. According to Rick Thoman of the National Weather Service in Fairbanks, Alaska, a buoy (64760) just 180 miles from the Pole, at 87.4°N, 154.4°E, reported a 1200 UTC December 30, 2015 temperature of -0.1°C with a -1.6°C dewpoint. Looking at the obs available for the past few days, there is nothing obviously bogus: the buoy was reporting -25°C two days ago. Bob Henson tweeted this fact on Tuesday: reanalysis maps dating back to 1948 (courtesy Steven Cavallo, University of Oklahoma) show only three cases where the North Pole Temperature reached the freezing mark or above in December (and no cases in January - March.) Andrew Freedman of Mashable has more on this freak Arctic warm wave in a Tuesday post.


Figure 4. Temperature analysis from the 00 UTC December 30, 2015 run of the GFS model, showing temperatures near freezing (aqua colors) penetrating very close to the North Pole. These temperatures are about 20°C (36°F) above average. Image credit: University of Maine Climate Reanalyzer.

Jeff Masters

Flood Winter Weather

U.S. Reeling From Violent Tornadoes, Epic Flooding, Winter Weather, and Weird Heat

By: Bob Henson and Jeff Masters , 10:54 PM GMT on December 28, 2015

Wild weather continued to plaster the nation’s midsection on Monday as a multi-barreled storm system shifted eastward. Thankfully, the severe weather threat has ramped down somewhat, with the highest risks now shifting to river and flash floods--from eastern Oklahoma to the Appalachians--and snow and ice, from Nebraska to New England. More than 40 weather-related deaths have been reported since Wednesday. The storminess is related to a gradual realignment of the large-scale pattern over North America, as described in detail by wunderblogger Steve Gregory in his Monday afternoon post. A stunningly warm, moist air mass across the eastern and southern U.S.--by some measures the most tropical on record for early winter--is in the process of being displaced by a strong upper-level storm moving into the central states, bringing much more seasonable cold.


Figure 1. Damage from the tornado that struck Rowlett, Texas, on Saturday evening, December 26, 2015. The tornado was rated at least EF3. Image credit: AP Photo/David Warren.

North Texas cleans up from Saturday’s deadly tornadoes
Ahead of a strong cold front in west Texas, supercell thunderstorms that ripped across the sprawling eastern part of the Dallas area spawned several tornadoes that killed at least 11 people. One violent tornado that killed eight people in Garland was rated EF4, while “at least EF3” damage was found in Rowlett, just east of Garland, due to the same tornado or one that closely followed. Two people died in Copeland, about 15 miles to the northeast, where EF2 damage was documented. Several other weaker tornadoes struck North Texas. According to the Dallas Morning News, as many as 1000 structures were damaged across north Texas, many of them severely. The storms were fed by a very strong upper-level jet as well as unusually high instability for December (around 3000 joules per kilogram, which would be concerning in springtime, much less wintertime). Temperatures reached 80°F in Dallas just hours before the tornadic supercell arrived, with a summerlike dew point of 67°F.

The widespread persistence of warm, humid conditions over the last few days has led to an unusual U.S. stretch of severe weather for December, including tornadoes from Mississippi to Michigan on Wednesday. The EF1 tornado that touched down in Canton, Michigan on December 23 was Michigan's first December tornado on record. If tornadoes are confirmed on Monday, it will be the sixth calendar day in a row with at least one U.S. tornado reported, tying a monthly record set on December 22-27, 1982, during the “super El Niño” of 1982-83. (The streak would be even longer if we counted early-morning tornadoes on December 23 as part of the December 22 “tornado day”, per NOAA recordkeeping.) Another tragic milestone: 2015 is the first year in records going back to 1875 that has seen more confirmed tornado-related deaths in December than in the rest of the year combined. The only other year with December having more deaths than any other single month was 1931, according to statistics analyzed by Harold Brooks (NOAA National Severe Storms Laboratory).


Figure 2. A 10” snowfall in Clovis, NM, resulted in drifts reaching 9 feet over the weekend, thanks to sustained winds that reached 45 mph with gusts reported to 82 mph at the Clovis airport. Fierce winds and blowing snow continued on Sunday, December 27, 2015. Image credit: wunderphotographer mneff267.

Winter weather shifting from High Plains to Midwest, Northeast
While severe weather rumbled across east Texas on Sunday, the western part of the state was dealing with a crippling blizzard that extended into eastern New Mexico, while freezing rain knocked out power to tens of thousands of western Oklahomans. Exceptionally strong winds--gusting above 70 mph in some areas--have led to near-zero visibilities and drifts of 6 feet or more, paralyzing travel across the region. Roswell, NM, had racked up 12.3” for the day by 8 pm CST Sunday, topping its one-day record of 11.5”; the two-day total of 15.5" was approaching Roswell's two-day record of 16.9”. Lubbock, TX, picked up 2.7” between 6 and 7 pm CST Sunday, pushing its storm total to 9.2”. The city’s heaviest-on-record storm total of 16.9” was picked up on January 20-21 during (you guessed it) the super El Niño of 1982-83.

As the upper-level storm and associated low head northeastward on Monday, more snow and ice is plastering a swath extending from Kansas and Nebraska to Wisconsin and Michigan. A mix of sleet, snow, and freezing rain is bedeviling parts of the Great Lakes, including the Chicago and Detroit areas. A band of heavier snow (6” to 12” in spots), coupled with freezing rain in some areas, is expected from northern Wisconsin into much of Maine.

Massive flooding hits Missouri and Illinois, killing 13
The weekend storm brought incredibly heavy rains to eastern Oklahoma, northwest Arkansas, and Southwest Missouri, with 10.0" falling in a 30-hour period ending Sunday evening on the south side of Springfield, Missouri. The heavy rains drove rivers in Illinois, Missouri, Oklahoma, and Arkansas above major flood stage, with the Illinois River reaching its highest crest on record at two locations. On Sunday, Governor Jay Nixon declared a state of emergency in Missouri due to heavy flooding all across the state, and urged Missourians in flood-affected areas to not drive into flooded roadways and avoid travel if possible. Eight people died Saturday night in Missouri in floods; six of the deaths occurred in two separate incidents where cars drove into flooded roadways in Pulaski County and were swept away by water. In southern Illinois, three adults and two children drowned Saturday evening when their car was swept away and sank in a rain-swollen creek. Mercifully, the rains have ended in Missouri and dry weather is expected the rest of the week.


Figure 3. Observed precipitation amounts for the 3-day period ending on Monday, December 28, 2015, at 4 pm EST. Rainfall amounts of 6"+ were widespread across eastern Oklahoma, northwest Arkansas, southwest Missouri and central Illinois, with some areas seeing 10"+. Image credit: NOAA/NWS.

A historic flood is building on the Mississippi River
The updated flood forecasts for the Mississippi River issued Monday afternoon by NWS River Forecast Center are about two feet higher than the forecasts issued on Sunday. Nearly all of the Lower Mississippi is expected to enter major flood stage over the next few weeks, as are the lower portions of two main tributaries, the Ohio and Arkansas Rivers. The Mississippi River near St. Louis was already near flood stage late last week due to excessive rains of 2 - 4" (400 - 600% of average) that fell during the past two weeks farther upstream in Iowa, Wisconsin, and Minnesota. A massive pulse of flood waters from the epic December 26 - 28 rains will pile into the Mississippi River over the next few days, bringing the river to flood levels that will be the highest on record outside of the usual spring to early summer flood season. The Mississippi River at St. Louis was at moderate flood stage on Monday afternoon, and is forecast to crest on Wednesday at the second highest level ever observed, just five feet below the all-time record set during the disastrous flood of 1993. Flood records at this location extend back to 1785. Downstream from St. Louis, the Mississippi River is forecast to crest late this week in Chester, Cape Girardeau, and Thebes at the highest levels ever recorded. NOAA warns that at the flood levels expected, the Degognia, Fountain Bluff, Stringtown, and Prairie DuRocher levees will be overtopped near Chester. NOAA projects that the massive flood crest will propagate downstream to the Gulf of Mexico during the first three weeks of January, bringing flood heights that are expected to be between the 2nd highest and 4th highest on record all the way to Louisiana.


Figure 4. The Mississippi River just downstream of St. Louis at Chester was at moderate flood stage on Monday afternoon, and is forecast to crest on Thursday at the highest level ever observed--exceeding the disastrous flood of 1993. Flood records at this location extend back to 1844. Image credit: NOAA/AHPS.

On January 20, the flood crest is expected to arrive in New Orleans, bringing the Mississippi River to its 17-foot flood stage in the city, just 3 feet below the tops of the levees. In past years, though, when the river has been forecast to rise to 17 feet in the city, the Army Corps of Engineers has opened up the Bonnet Carre Spillway in St. Charles Parish, which diverts water into Lake Pontchartrain and keeps the river from reaching flood stage in New Orleans. The Corps may also be forced to open the Morganza Floodway in Pointe Coupee Parish, which would divert water down the Atchafalaya River. Opening this spillway has a considerably higher cost than opening the Bonnet Carre Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Floodway. The Corps also has the option of increasing the flow of Mississippi River water into the Atchafalaya at the Old River Control Structure in Concordia Parish. Operating the Old River Control Structure in this way always makes me nervous, as I explained in my 2011 blog post, America's Achilles' heel: the Mississippi River's Old River Control Structure. The Monday afternoon forecast from the NWS River Forecast Center predicted that the Mississippi River would crest at Red River Landing, where the Old River Control Structure is located, on January 19. The predicted crest of 62.5' is just 0.9' below the all-time record crest of 63.39' set on May 18, 2011. A water level this high has a good chance of forcing the Army Corps to open the Morganza Floodway in order to relieve pressure on the Old River Control Structure. Both the Bonnet Carre Spillway and Morganza Floodway were opened in May 2011, when the highest flood crests ever observed on the Lower Mississippi arrived. This flood cost over $2 billion; I expect the damage from the December 2015 - January 2016 Mississippi River flood will run into the hundreds of millions.


Figure 5. Existing flood stage on December 28, 2015 (inner colored square) and predicted maximum flood stage (outer colored square region around the inner colored square) for the Lower Mississippi River and two tributaries (the Arkansas and Ohio Rivers) near where they join the Mississippi. I've added a numerical ranking on the right side of the squares to indicate where a top-ten flood crest in recorded history is expected. Two gauges are expecting their highest floods on record (Cape Girardeau and Thebes), and most of the Lower Mississippi is expecting a top-five highest flood crest on record. Where the Ohio River joins the Mississippi at Cairo, Illinois, the Ohio River is forecast to crest on January 5 at the third highest level on record; downstream from Little Rock, Arkansas, the Arkansas River is predicted to crest on Friday at the third highest level on record near its confluence with the Mississippi. Image credit: NWS River Forecast Center.

Recapping the Big Christmas Warm
Hundreds of records were buried by sunshine, warmth, and humidity instead of white-Christmas snowfall all across the eastern U.S. during the holidays, especially on Thursday and Friday. Christmas Day was the apex for the north-south breadth of warmth, with record highs set from Florida (82°F in Jacksonville) to Maine (62°F in Portland). Many records on Thursday and Friday were smashed by margins of 10°F or more. The Christmas Eve readings of 72°F at Albany, NY, and 68°F at Burlington, VT, both set all-time records for December. As noted by WU weather historian Chris Burt, these are truly impressive records given the late date in a month that gets progressively colder, not to mention the long periods of record at both sites (since 1883 in Burlington and 1874 in Albany). Chris adds that Philadelphia has seen eight days this month through Sunday with record daily highs: “Not since records began in Philadelphia back in 1874 has any other month of any single year experienced as many daily record highs as this December!” The capital of Christmas commerce, New York City, basked in record warmth of 72°F on Thursday and 66°F on Friday. As of Sunday, Central Park had yet to get below 32°F this fall or winter; its monthly average (12/1 – 12/26) of 52.0°F was running at an astonishing 13.8°F above normal and 7.9°F above the previous December record, going back to 1871. A cooldown this week will reduce that value, but a warmest-on-record December is all but certain for much of the eastern U.S. It’s no wonder that flowers and shrubs are blossoming from Washington to New York.

For the period 12/1/ through 12/26, NOAA’s U.S. Records site shows a phenomenal 3879 daily record highs and 5301 record warm lows, compared to 166 record cold highs and 159 record lows. Despite the intense cold in the eastern U.S. early in 2015, this year will end up with more than two and a half times as many U.S. daily record highs as lows, just one more statistic for a year that is wrapping up in remarkable fashion.


Figure 6. Rescue teams wade through flood waters that have inundated homes in the Huntington Road area of York after the River Foss burst its banks, on Monday, December 28, 2015 in York, United Kingdom. Severe flooding has affected large parts of northern England, with homes and businesses in Yorkshire and Lancashire evacuated as rivers burst their banks. More heavy rain is forecast as dozens of severe flood warnings remain in place. Image credit: Jeff J. Mitchell/Getty Images.

Floods, holiday warmth extend to Britain and beyond
Northern England continues to deal with relentless bursts of rain and resulting floods. The accounting firm KPMG estimates the cost of the disruption to Britain’s economy at up to 5.8 billion pounds (roughly $8.6 billion US). More heavy rain is expected on Wednesday. The venerable Central England Temperature index--the world’s oldest continuous instrumented record of temperature--remains on track to set its warmest December reading in more than 350 years. The estimated average from 12/1 to 12/27 is at 9.8°C (49.6°F), which is 5.0°C (9.0°C) above the norm. Other European nations are also likely to set records for December warmth, including the Netherlands.

Bob Henson (tornadoes, blizzard, record warmth) and Jeff Masters (flooding)

Flood Tornado Winter Weather Heat

Punishing Four-Season Storm Grips U.S. during the Holiday Week, Killing Over 40

By: Bob Henson and Jeff Masters , 3:24 AM GMT on December 28, 2015

An incredible variety of weather hazards made their presence felt over Christmas weekend across the central U.S., from blizzard to tornado to freezing rain to flash flooding and river floods. More than 40 weather-related deaths have been reported since Wednesday. The multi-day storminess is related to a gradual realignment of the large-scale pattern over North America. A stunningly warm, moist air mass across the eastern and southern U.S.--by some measures the most tropical on record for early winter--is in the process of being displaced by a strong upper-level storm across the West, bringing much more seasonable cold. There’s been so much remarkable weather over the weekend that it’s difficult to summarize in a single blog post, but here are some highlights.


Figure 1. Damage from the tornado that struck Rowlett, Texas, on Saturday evening, December 26, 2015. The tornado was rated at least EF3. Image credit: NWS/Fort Worth.

Deadly tornadoes strike near Dallas on Saturday
Ahead of a strong cold front in west Texas, supercell thunderstorms that ripped across the sprawling eastern part of the Dallas area spawned several tornadoes that killed 11 people. One violent tornado that killed eight people in Garland was rated EF4, while “at least EF3” damage was found in Rowlett, just east of Garland. Two people died in Copeland, about 15 miles to the northeast, where EF2 damage was documented. According to the Dallas Morning News, as many as 1000 structures were damaged across north Texas, many of them severely. The storms were fed by a very strong upper-level jet as well as unusually high instability for December (around 3000 joules per kilogram, which would be concerning in springtime, much less wintertime). Temperatures reached 80°F in Dallas just hours before the tornadic supercell arrived, with a summerlike dew point of 67°F.

The widespread persistence of warm, humid conditions over the last few days has led to a unprecedented U.S. stretch of severe weather for December, including tornadoes from Mississippi to Michigan on Wednesday. Sunday was the seventh day in a row with at least one U.S. tornado reported--the first such week-long stretch for any December in NOAA Storm Prediction Center records dating back to 1950, as noted by WU contributor Dr. Phil Klotzbach. The previous record string of six days, December 22-27, 1982, occurred during the “super El Niño” of 1982-83. Another tragic milestone: 2015 is the first year in records going back to 1875 that has seen more confirmed tornado-related deaths in December than in the rest of the year combined. The only other year with December having more deaths than any other single month was 1931, according to statistics analyzed by Harold Brooks (NOAA National Severe Storms Laboratory).


Figure 2. From Ropesville, TX, about 20 miles southwest of Lubbock, on Sunday, December 27, 2015: “Blizzard conditions hit this area last night with 50 - 60 mph winds and they haven't let up. These mailboxes have taken a nice beating over the last 15 or so hours.” Image credit: wunderphotographer docshovel39.

Blizzard pummels southern High Plains
As severe storms continued to rumble across east Texas on Sunday, the western part of the state was dealing with a crippling blizzard that extended into eastern New Mexico, while freezing rain knocked out power to tens of thousands of western Oklahomans. Exceptionally strong winds--gusting above 70 mph in some areas--have led to near-zero visibilities and drifts of 6 feet or more, paralyzing travel across the region. Roswell, NM, had racked up 12,3” for the day by 8 pm CST Sunday, topping its one-day record of 11.5”; the two-day total of 15.5" was approaching Roswell's two-day record of 16.9”. Lubbock, TX, picked up 2.7” between 6 and 7 pm CST Sunday, pushing its storm total to 9.2”. The city’s heaviest-on-record storm total of 16.9” was picked up on January 20-21 during (you guessed it) the super El Niño of 1982-83. As the upper-level storm and associated low head northeastward on Monday, more snow and ice will plaster a swath extending from Kansas to Wisconsin and Michigan.

Massive flooding hits Missouri and Illinois, killing 13
Only days after major flooding across central and northern Alabama late last week, the weekend storm brought incredibly heavy rains to eastern Oklahoma, northwest Arkansas, and southwest Missouri, with 10.0" falling in a 30-hour period ending Sunday evening on the south side of Springfield, Missouri. On Sunday, Governor Jay Nixon declared a state of emergency in Missouri due to heavy flooding all across the state, and urged Missourians in flood-affected areas to not drive into flooded roadways and avoid travel if possible. Eight people died Saturday night in Missouri in floods; six of the deaths occurred in two separate incidents where cars drove into flooded roadways in Pulaski County and were swept away by water. In southern Illinois, three adults and two children drowned Saturday evening when their car was swept away and sank in a rain-swollen creek. An additional 1 - 2" of rain is expected over most of Missouri and Arkansas by Monday evening, but dry weather is mercifully expected the rest of the week. The 4.87” of rain in St. Louis on Saturday made it the third wettest calendar day in records going back to 1874. More rain on Sunday pushed the city to its wettest year on record, beating 57.96” in 2008.


Figure 3. Observed precipitation amounts for the 48-hour period ending on Sunday, December 27, 2015, at 8 pm EST. Rainfall amount of 6"+ were widespread across eastern Oklahoma, northwest Arkansas, and southwest Missouri, with some areas seeing 10"+. Image credit: NOAA/NWS.

Historic flood imminent on the Mississippi River
The Mississippi River near St. Louis was near flood stage late last week due to excessive rains of 2 - 4" (400 - 600% of average) that fell during the past two weeks farther upstream in Iowa, Wisconsin, and Minnesota. A massive pulse of flood waters from this weekend's epic December rains will pile into the Mississippi River over the next few days, bringing the river to flood levels never recorded this time of year. The Mississippi River at St. Louis was approaching moderate flood state on Sunday evening, and is forecast to crest on Wednesday at the second highest level ever observed, just five feet below the all-time record set during the disastrous flood of 1993. Flood records at this location extend back to 1785. It’s worth noting that, of the top 40 Mississippi River flood crests in St. Louis history, only one has occurred in a winter month (Dec-Feb). That was the #9-ranked crest of 39.27”, recorded (when else?) on December 7 during the super El Niño of 1982-83.

Downstream from St. Louis, the Mississippi River is forecast to crest late this week in Chester and Cape Girardeau, Missouri above the all-time record 1993 flood; NOAA warns that at the flood levels expected, the Degognia and Fountain Bluff Levees will be overtopped. NOAA projects that the massive flood crest will propagate downstream to the Gulf of Mexico next week, bringing flood heights that are expected to be between the 2nd highest and 4th highest on record all the way to Baton Rouge, Louisiana.

On January 20, the Mississippi flood crest is expected to arrive in New Orleans, bringing the river to its 17-foot flood stage in the city, just 3 feet below the tops of the levees. In past years, though, when the river has been forecast to rise to 17 feet in the city, the Army Corps of Engineers has opened up the Bonnet Carre Spillway in St. Charles Parish, which diverts water into Lake Pontchartrain and keeps the river from reaching flood stage in New Orleans. According to a December 25 article by Mark Schleifstein of NOLA.com, this option will be discussed on Monday at an Army Corps flood "flood fight" meeting, along with the less likely possibility of opening the Morganza Floodway in Pointe Coupee Parish, which would divert water down the Atchafalaya River. Opening this spillway has a considerably higher cost than opening the Bonnet Carre Spillway, due to the large amount of agricultural lands that would be flooded below the Morganza Spillway. The Corps also has the option of increasing the flow of Mississippi River water into the Atchafalaya at the Old River Control Structure in Concordia Parish. Operating the Old River Control Structure in this way always makes me nervous, as I explained in my 2011 blog post, America's Achilles' heel: the Mississippi River's Old River Control Structure. Both the Bonnet Carre Spillway and Morganza Floodway were forced to open in May 2011, due to the highest flood crests ever observed on the Lower Mississippi. This flood cost over $2 billion; I expect the damage from the December 2015 - January 2016 Mississippi River flood will run into the hundreds of millions.


Figure 4. The Mississippi River at St. Louis was approaching moderate flood state on Sunday evening, and is forecast to crest on Wednesday at the second highest level ever observed, just five feet below the all-time record set during the disastrous flood of 1993. Flood records at this location extend back to 1785. Image credit: NOAA/AHPS.

The Big Christmas Warm
Hundreds of records were buried by sunshine, warmth, and humidity instead of white-Christmas snowfall all across the eastern U.S. during the holidays, especially on Thursday and Friday. Christmas Day was the apex for the north-south breadth of warmth, with record highs set from Florida (82°F in Jacksonville) to Maine (62°F in Portland). Many records on Thursday and Friday were smashed by margins of 10°F or more. The Christmas Eve readings of 72°F at Albany, NY, and 68°F at Burlington, VT, both set all-time records for December. As noted by WU weather historian Chris Burt, these are truly impressive records given the late date in a month that gets progressively colder, not to mention the long periods of record at both sites (since 1883 in Burlington and 1874 in Albany). Chris adds that Philadelphia has seen eight days this month through Sunday with record daily highs: “Not since records began in Philadelphia back in 1874 has any other month of any single year experienced as many daily record highs as this December!” The capital of Christmas commerce, New York City, basked in record warmth of 72°F on Thursday and 66°F on Friday. As of Sunday, Central Park had yet to get below 32°F this fall or winter; its monthly average (12/1 – 12/26) of 52.0°F was running at an astonishing 13.8°F above normal and 7.9°F above the previous December record, going back to 1871. A cooldown this week will reduce that value, but a warmest-on-record December is all but certain for much of the eastern U.S. It’s no wonder that flowers and shrubs are blossoming from Washington to New York.

At this writing, NOAA’s U.S. Records site had not yet been updated with the many records after Dec. 24, but for the period 12/1 – 12/24, December saw a phenomenal 3164 daily record highs and 4511 record warm lows, compared to 147 record cold highs and 147 record lows. Despite the intense cold in the eastern U.S. early in 2015, this year will end up with more than twice as many U.S. daily record highs as lows, just one more statistic for a year that is wrapping up in remarkable fashion.

Bob Henson (tornadoes, blizzard, record warmth) and Jeff Masters (flooding)


Figure 5. With the lower Manhattan skyline in the background, Meg Roebling runs through Brooklyn Bridge Park in New York on a record-warm Christmas Eve, Thursday, Dec. 24, 2015. Image credit: AP Photo/Kathy Willens.

Extreme Weather Blizzard Flood Torn Tornado Winter Weather

Tornadoes Rake Mississippi Delta; More Storminess Ahead

By: Bob Henson and Jeff Mast ers , 5:31 PM GMT on December 24, 2015

One of the longest-tracked tornadoes ever observed in December carved its way from northwest Mississippi into southwest Tennessee on Wednesday. The twister, likely to be rated at least an EF3 after damage surveys on Thursday, was part of an unusually far-flung year-end outbreak of severe storms that extended from the Gulf Coast to the Great Lakes. Although several tornadoes were reported as far afield western Illinois and central Indiana--and even Michigan experienced its first December tornado on record--the bulk of the 29 preliminary tornado reports received by NOAA’s Storm Prediction Center (SPC) came from northern Mississippi and adjacent areas. At least 10 deaths were reported by midday Friday, most of them tornado-related.

By far the most destructive storm of the day was the long-lived supercell that produced the long-track tornado noted above, as well as several others. Greg Carbin, warning coordination meteorologist at SPC, speculates that this storm was in a small region where instability from warm, moist surface air and very high vertical wind shear came together for nearly ideal supercell conditions. “Elsewhere, there were numerous supercell structures and fast-moving line segments producing damage,” says Carbin. “However, based on my interpretation of the character of radar reflectivity during the event, many of the storm updrafts were ‘stretched out’ by the intense vertical shear across the region.”


Figure 1. Tornado east of the Shack Up Inn outside Clarksdale, Mississippi, on December 23, 2015. This is probably the same tornado that stayed on the ground for 150 miles and later killed one person in Holly Springs, Mississippi. Image credit: Guy Malvezzi.


Figure 2. Vehicles blown off the road in Holly Springs, Mississippi on December 23, 2015. A seven-year-old boy was killed in the town by the tornado. This photo also illustrates the danger of being parked beneath an overpass when a potentially tornadic thunderstorm is approaching. Image credit: Dan Smith and Karla Fisher.




Figure 3. Radar reflectivity (top) and Doppler velocity (bottom) of the supercell thunderstorm that spawned the Holly Springs, Mississippi tornado as seen at 5:28 pm EST December 23, 2015.


How far can a tornado go?
Continuous tornado paths longer than 100 miles are uncommon, and they can be a challenge to confirm, especially in rural areas. In many cases, a long-lived supercell will produce several tornadoes in quick succession (also known as a tornado “family”), with brief breaks in between each damage path. The infamous Tri-State Tornado of March 18, 1925, was long envisioned as a single twister producing a 219-mile-long path, but more likely it was a tornado family with one dominant member. A thorough analysis led by former SPC forecaster Robert Johns found 32 gaps along the Tri-State path, each at least 1 mile long. The researchers concluded that a 151-mile segment from Bollinger County, Missouri, to Pike County, Indiana, was most likely to be the longest continuous path from this tornado family.

The longest confirmed tornado track during winter (December-February) is the 122-mile-long path from a tornado that plowed through northern Arkansas during the Super Tuesday outbreak on February 5, 2008. Looking throughout the year, there have been at least 26 tornadoes of at least F3/EF3 strength since 1950 with path lengths of more than 120 miles, according to Harold Brooks (National Severe Storms Laboratory).


Figure 4. Preliminary damage track of the violent tornado that cut a long swath across northwest Mississippi into southwest Tennessee on Wednesday, Dec. 23, 2015. An updated track will be produced after storm surveyors assess the damage. Image credit: NWS/Memphis.

2015 no longer the nation’s safest tornado year
As a result of Thursday’s activity, the year 2015 to date now has close to 20 tornado-related deaths. This puts 2015 out of the running for the least number of U.S. tornado fatalities for a given year in records going back to 1875. The year with the lowest death toll remains 1910, which saw just 12 tornado-related fatalities. The year 1986 is in second place, with 15, and in 2009 there were just 21 tornado-related deaths.


Figure 5. Thunderstorms (mostly non-severe) are lined up along the jet stream from southern Louisiana to the mid-Atlantic at 1630Z (11:30 am EST) on Thursday, December 24, 2015. Image credit: NOAA-NASA GOES Project.

More storms in the offing through the holiday weekend
Thunderstorms will pose less of a threat on Thursday and Friday than on Wednesday, although in some areas they’ll accentuate the presence of a record-warm, record-moist air mass. SPC has only a marginal risk of severe weather for Thursday from the lower Mississippi Delta to the Delmarva region, with a smaller marginal risk from northeast Texas to southwest Tennessee. Another marginal-risk area on Friday extends from northeast Texas to most of Kentucky and Tennessee. More intense activity may develop over the weekend, with SPC’s Day 3 outlook for Saturday already including a slight risk for a large part of Texas, and parts of east Texas and Louisiana outlooked for possible severe weather on Sunday. A strong cold front will be plowing across the Southern Plains by then, which could shift the odds toward wind-packing squall lines as opposed to supercells.

Off-the-charts record warmth for Christmas
The well-advertised holiday warm wave continues to astound, with “instant” record highs set overnight in many locations from the Great Lakes to the Northeast. Readings at midday Friday were already into the 70s Fahrenheit from southeast New York to the Gulf Coast, with widespread 80s across Florida. Some of the daily record highs along and near the East Coast on Thursday will be 10°F or more beyond the warmest Christmas Eve in more than a century of recordkeeping. Breaking a longstanding daily record by more than 10°F is noteworthy in itself, and the intense zone of high pressure off the southeast U.S. coast is uncannily similar to the Bermuda highs common in midsummer! Given the intense interest in holiday weather and the many family gatherings under way, we can expect this bizarre weekend to spur countless dinner-table conversations about climate change and “global weirding.” A warm wave like this doesn’t “prove” climate change; it is one manifestation of the weather that results from natural variations such as El Niño playing out in a global atmosphere that is being warmed, moistened, and shifted by ever-increasing amounts of greenhouse gases. Like the spectacular warm wave of March 2012, which brought 90°F readings to Michigan, the tropical Christmas Eve 2015 could serve as an excellent candidate for attribution research--the attempt to unravel how much long-term climate change raises the odds of a particular weather event.

Have a great holiday weekend, everyone!

Bob Henson and Jeff Masters

Tornado Extreme Weather

Severe Weather Targets Mississippi, Tennessee Valleys

By: Bob Henson , 5:49 PM GMT on December 23, 2015

Just a day before Christmas Eve, the threat of tornadoes is darkening the pre-holiday mood across parts of the South. In its outlook updated at 10:30 am CDT, NOAA’s Storm Prediction Center (SPC) is projecting a moderate risk of severe weather for Wednesday from eastern Arkansas across northern Mississippi and Arkansas into western Tennessee and Kentucky, with lesser risks over a large surrounding area covering most of the nation between the Mississippi and the Appalachians. In the moderate risk area, long-track tornadoes are a distinct possibility. On Wednesday morning, The Weather Channel’s Dr. Greg Forbes raised the TOR:CON level to 8 across northern Mississippi and Alabama and western Tennessee, calling a tornado outbreak “likely.” According to TWC’s Michael Butler, this is the nation’s first TOR:CON of 8 since April 28, 2014. By late morning, several bands of severe thunderstorms had already developed from Illinois to Arkansas, with scattered storms further to the southeast. Two tornado watches were in effect, and more than two dozen tornado warnings had already been issued. Major tornado outbreaks in December are uncommon but not unheard of. The last "Moderate Risk" forecast for severe weather issued by the SPC in December was in 2013; there were also two "Moderate Risk" forecasts issued in December 2012.


Figure 1. NOAA/SPC severe weather outlook for Wednesday, December 23, 2015, updated at 10:30 am CDT.

A broad channel of warm, soupy air from the Gulf of Mexico has streamed north across much of the eastern U.S. over the last 24 hours. Both temperatures and dew points have risen into the 50s as far north as Detroit and New York and into the low 70s over Louisiana. Later today, warm, humid air feeding into the moderate-risk area will combine with the rich moisture to produce increasingly unstable surface conditions. The instability will not be extreme, but in wintertime even moderate levels of instability are enough to produce tornadic supercell storms if there is strong wind shear present. The latter will be furnished by a sprawling upper-level trough over the western U.S., with jet-stream winds well above 120 mph. A strong upper-level impulse within the trough will shoot northeast across the moderate-risk area later today, providing the dynamics to support widespread severe weather.


Figure 2. WunderMap depiction of jet-stream winds in knots (multiply by 1.15 for mph) at the 300-mb level (around 30,000 feet) projected by the GFS model for 21Z (3:00 pm CST) on Wednesday, December 23, 2015. The sharp kink in the jet centered over eastern Arkansas and western Tennessee will act intensify updrafts and wind shear over the region.

Across the moderate risk area, supercell thunderstorms will pose a particular risk of dangerous tornadoes on Wednesday afternoon and evening. On Thursday, a broad swath of less intense thunderstorms will extend unusually far to the northeast for this time of year. Thunder and lightning could serve as a stand-in for a white Christmas Eve as far north as Albany and Boston. Instability will be somewhat lower on Thursday, and the wind configuration less favorable, so the Day 2 outlook released by SPC on Wednesday morning projects only a marginal risk for severe weather with these storms from the central Gulf Coast to the Washington, D.C., area. As the upper-level trough recharges across the West over the weekend, and another pulse of springlike air moves in, additional severe weather could erupt over eastern Texas and adjoining states.

December can be dangerous for severe weather over the South
Ready access to warm, moist air from the Gulf of Mexico means that severe weather is a risk over the U.S. South even during the cold season. Wednesday’s activity is pushing the typical northern edge of such outbreaks. The most recent significant tornado outbreak (10+ tornadoes) during Christmas week was on December 21, 2013, centered over the Mississippi Delta. Two fatalities were associated with at least 14 twisters that day. The largest outbreak on Christmas Day occurred on December 25, 2012, when more than two dozen Christmas Day tornadoes struck from Texas to North Carolina. On New Year’s Eve 2010, an outbreak with 32 tornadoes included seven EF3s, one of which killed four people in Arkansas (with nine fatalites in all that day). The five deadliest U.S. December tornadoes have been summarized by weather.com, including an F4 twister that killed 11 near Tuscaloosa, AL, on December 16, 2000, and another F4 that took 11 lives at Murphysboro, IL, on December 18, 1957. The most devastating of the lot was the tornado that swept across Vicksburg, MS, on December 5, 1953, killing 38 people and injuring 270.

Record-melting heat still on tap for the holiday weekend
More than a month ago, seasonal prediction models and the record from past strong El Niños pointed toward the chance of a December “warm wave” for much of eastern North America. Those signals are being confirmed in spectacular fashion, as hundreds of daily record-warm highs and lows--and a number of monthly records--are destined to fall over the next several days over much of the United States east of the Mississippi. With overnight temperatures so warm, some record highs for Christmas Eve and Christmas Day may fall at the stroke of midnight! For Thursday (Christmas Eve), WU is predicting record highs on par with typical early-autumn readings, including 56°F in Portland, ME; 68°F in Boston, MA; 72°F in New York, NY; 73°F in Philadelphia, PA; 74°F in Washington, D.C.; and 79°F in Norfolk, VA. A half-hearted cool front will push the warmest air toward the southeast by Friday (Christmas Day), but it’ll still remain unusually mild across parts of the Northeast and downright springlike all weekend further to the south, with 70s from North Carolina to Georgia and 80s in Florida. For more background on the warm weather that’s bathed several continents this month, see our post from last Monday.

Wunderblogger Steve Gregory has a new Wednesday afternoon post, Record Warmth – Severe T-Storms - But Pattern Change on the Way. Another Wunderblogger, Lee Grenci, weighs in today on the "clash of air masses" explanation for severe weather.

Stay safe, everyone!

Bob Henson

Severe Weather Extreme Weather

Holiday Heat is On in Europe, Australia, Eastern U.S.

By: Bob Henson , 5:36 PM GMT on December 21, 2015

The year 2015 is is just days away from nabbing the top spot as the world’s warmest in more than a century of recordkeeping. As if to emphasize the point, the year is wrapping up with a blaze of December heat records around the globe. Some of the most exceptional numbers are being tallied over eastern North America, Europe, and Australia, which all ran quite warm in November as well. To be sure, some individual days have been standouts--and there are more of those to come--but the truly striking aspect of this month’s heat is its tenaciousness. We remain in the firm grip of a strong El Niño, as well a strongly positive North Atlantic Oscillation that’s keeping Arctic air on a tight leash at high latitudes.


Figure 1. Departures from average temperature across the contiguous U.S. for the period Dec. 1 – Dec. 19, 2015. Image credit: NWS Climate Prediction Center.

Eastern U.S.: Humidity, warmth, and thunder for the holidays
It’s been an absurdly mild December over most of the United States. Figure 1 shows above-average readings across nearly all of the country. The biggest departures can be seen over the Upper Midwest. However, those smaller departures you see over the Northeast are actually more climatologically significant, because the climate there doesn’t tend to vary as sharply from day to day and week to week. Moreover, chilly air arriving in the Midwest over the next few days should help tamp down the departures there, but not so much in the East. Amazingly, New York’s Central Park has only had one freeze so far, if you can call it that--a paltry 32°F on November 24--and there may be no subfreezing temperatures to come before 2016 arrives. New York is just one of the nation’s big eastern cities likely to streamroll longstanding records for their all-time warmest December. Among the candidates:



These records might not be in such jeopardy if an Arctic air mass were approaching before year’s end. Instead, another slug of unseasonably mild, humid air will be streaming from the tropics across the southern and eastern U.S. later this week. Often when such an air mass approaches in winter, it will glide above an entrenched surface layer of cold air. But with snow cover nil this year, and preexisting Arctic air absent, the tropical surge has a better chance of mixing all the way to the surface. There could be severe weather across the Mississippi Valley on Wednesday, and dew points approaching or topping 60°F will make it feel oddly humid as far north as Boston by Christmas Eve. For millions of people across the southern and eastern U.S., Christmas Eve and/or Christmas Day will be the warmest in living memory, and in some cases the warmest in more than a century of recordkeeping (see this weather.com roundup for more details). Even with the warmth, it may not be the sunniest of holidays, as the rich moisture will swaddle many places in dank clouds and fog.

Even Mount Washington, NH--notorious for its extreme winter weather--may eclipse its warmest December temperature on record (47°F), if the WU forecast of 49°F on Christmas Eve is correct.


Figure 2. Potential record highs on Christmas Day—Friday, December 25, 2015. Image credit: weather.com.

This “warm wave” will extend far into eastern Canada. Temperatures may crawl above freezing at the southern tip of Hudson Bay by Wednesday, and relative mildness should envelop most of the Canadian Maritimes. The town of Churchill Falls, Labrador, has an average daily low of -15°F this time of year; on Christmas Eve, it may struggle to get below 26°F. Montreal and Ottawa are likely to smash records for their warmest Christmas Eve with readings well above 50°F, according to The Weather Network’s “Christmas Eve Blowtorch” outlook. Montreal occasionally gets a non-snowy holiday, but nearby ski areas are struggling because it won’t even be cold enough to make snow.

On the other side of the pond . . .
Across the North Atlantic, the warmth has been equally impressive. Three European nations with records of 150 years or longer--Finland, Sweden, and Estonia--have set or tied all-time national heat records for the month of December in recent days. Earth’s longest-running climate archive, the Central England Temperature Record, has a chance at the warmest December in its 357-year history. The CET average for the month to date (12/1 – 12/19) is 9.9°C, a phenomenal 5.1°C above the 1961-1990 mean and well above the warmest December on record (8.1°C in 1934 and 1974). London Heathrow has made it above 10°C (50°F) every day thus far in December, and that streak may continue through month’s end. Gardeners in Cornwall, England, have reported spring-flowering camellias in bloom months ahead of schedule.

Several other European nations are on track for a record-warm December, including the Netherlands and Germany. New all-time highs for December have been set in a number of capital cities, including Stockholm, Sweden (13.2°C); Riga, Latvia (11.8°C); Tallin, Estonia (11.7°C); and Helsinki, Finland (10.8°C). Nearly 100 stations across Germany have seen their highest daily minima for any December, said Michael Theusner (Klimahaus-Bremerhaven) in an email. “Even though not many all-time highs [for December] were broken, the duration of the warmth and its magnitude are exceptional,” he added. Germany’s monthly anomaly to date--5.4°C above average--is far beyond the peaks of around 4.0°C observed in 1934 and 1974.

Further south, a weekend burst of downslope southerly winds (the famed “foehn”) brought temperatures on Sunday up to balmy values along the northern slopes of the Alps and Pyrenees. These included 17.7°C (63.9°C) at Hohenpeissenberg, Germany and 16.3°C (61.3°F) at Brand, Austria, both at elevations of more than 3200 feet. The town of Pau, France, basked in 25.4°C (77.7°F) warmth. (Thanks go to weather records researcher Maximiliano Herrera for these statistics.) Ski resorts across the Alps are bracing for continued mildness throughout the holidays.


Figure 3. These images, taken exactly one year apart--0920 local time on Dec. 21, 2014 (top) and 2015 (bottom)--show the stark contrast in snow conditions at the ski resort of Grossarltal in central Austria. Image credit: ZAMG, courtesy Maximiliano Herrera.

For a truly toasty Christmas, head Down Under
If it seems just a bit too mild to be wrapping presents or roasting a holiday dinner, consider the hardy souls of Port Augusta, Australia (“Gateway to the Outback”). They had to deal with record December temperatures that vaulted to 47.2°C (117.0°F) on Saturday. For the first time in any December, the city of Adelaide saw four consecutive days of highs topping 40°C (104°F). The torrid air swept into New Zealand on Monday: the South Island city of Dunedin hit a scorching 34.6°C (94.3°F), more than 4°F above its prior December record of 32.2°C. Readings should tumble back to more seasonable levels later this week across Australia, with predicted highs for Christmas Day mostly in the 80s to low 90s Fahrenheit.

Jeff Masters will be back later this week with his definitive roundup of this year’s Category 5 tropical cyclones around the world. In the meantime, if you’ve never heard the voice of NOAA Weather Radio saluting the season, you’re in for an old-school automated treat. The winter solstice begins on Monday night at 11:48 pm EST. Happy holidays, everyone!

Bob Henson


Figure 4. Coping with pre-holiday (heat) stress in Adelaide, Australia, on December 19, 2015, the final day of an unprecedented four-day stretch of December days reaching 40°C (104°F). Image credit: Morne de Klerk/Getty Images.





Extreme Weather Climate Summaries

Common Thread at 2015 AGU Conference: The Big Melt

By: Bob Henson , 11:20 PM GMT on December 18, 2015

The weather story of this month is the record warmth swaddling much of eastern North America and Europe. We’ll have much more to say about that next week, but keeping with the warm theme for today, I’ll share a couple of melt-related tidbits that drew my attention at this year’s Fall Meeting of the American Geophysical Union, which Jeff Masters and I attended this week. This is the world’s largest gathering of Earth-related scientists, with more than 20,000 researchers, journalists, and others in attendance. Thousands of posters and talks cover the whole spectrum of Earth sciences--at any one moment, there can be 50 or more presentations going on. Various science journalists and WunderBlog commentors have done a great job of capturing the broad array of science presented this week. You can browse the enormous number of abstracts at the meeting website. Many of the presentations were recorded and are now available through AGU On Demand (free registration is required). Here's a full list of those recorded sessions. (Thanks for WU member spbloom for the tip.] If the drip-drip-drip of climate change news starts getting to you, there’s a handy remedy: Jeff’s AGU post from Wednesday, “The Top Ten Reasons to be Hopeful on Climate Change”.

Lots of red on the Arctic Report Card
NOAA introduced its 2015 Arctic Report Card with a press conference on Tuesday, viewable in archive form (as are all of the press conferences). The Arctic’s grades were not good. Our northern polar regions are failing--that is, failing to shield themselves from the relentless build-up of greenhouse gases. The polar year running from October 2014 to September 2015 was the warmest in more than a century of recordkeeping, with the region now 3°C (5.4°F) warmer than it was at the start of the 20th century. The minimum summer extent of Arctic sea ice, which occurred on September 11, was not a record--it ranked fourth lowest in the satellite era (starting in 1979). However, the maximum winter extent did set a record low, and that occurred on February 25, two weeks ahead of average and the second earliest max in the satellite era.

One of the lesser-known but still profound changes to the Arctic is the decline in June snow cover, which is decreasing at around 18% per decade. Because the northern sun is at its strongest in June, this decline means that a good deal less sunlight is being reflected from polar regions, thus allowing more absorption of heat at the surface.



Figure 1. Top: Average temperature for October 2014-September 2015 compared to the 1981-2010 average. All around the Arctic, temperatures were much warmer than average, with only Greenland and a small part of northeastern Canada near or below average. Bottom: Annual temperatures for the Arctic (blue line, representing 60°N - 90°N) and the globe (black line) since 1900. Arctic temperatures are more variable from year to year than global temperatures (bigger swings above and below average). But despite the variability, a trend is clear: the Arctic has warmed more than the globe as a whole. Image credit: climate.gov.


Figure 2. Permafrost is thawing across the Arctic, causing northern lands to sink or change shape. In Gates of the Arctic National Park, a bank of this lake thawed in the summer of 2014, allowing the Okokmilaga River to cut through and drain it to sea. Researchers from the University of Alaska Fairbanks and the University of Colorado presented new work at the AGU Fall Meeting on the speeded-up pace of permafrost melt across northern Alaska. Image credit: Howcheng/US National Park Service/Wikimedia Commons.

More than polar bears at risk
Polar bears are the poster creatures of climate change, which makes it easy to overlook how warming temperatures might affect other Arctic creatures. These impacts can be difficult to pin down, because there are complicated intersections between human-driven warming and other anthropogenic factors, such as variations in hunting rates over time and the build-up of oil and gas infrastructure. An increase in rain-on-snow events over the Arctic is already having noteworthy impacts on reindeer, which forage for vegetation beneath snow cover during winter. A record number of reindeer (about 20% of a herd of 300,000) died in the winter of 2013-14 on the Yamal Peninsula of Western Siberia. A team led by Bruce Forbes (University of Lapland) described its post-event research in an AGU poster. “More than a year later, participatory fieldwork with nomadic herders during spring-summer 2015 revealed that the ecological and socio-economic impacts from this extreme event will unfold for years to come,” the group reported. They’re now investigating whether the loss of sea ice in the Barents and Kara Sea is playing a role in the growing prevalence of rain-on-snow events. “There is an urgent need to understand whether and how ongoing Barents and Kara Sea ice retreat may affect the region’s ancient and unique social-ecological systems.”

The state of Arctic walrus is analyzed in detail in this year’s Arctic Report Card. Sea ice is an integral part of walrus life: adults hang out and mate along the edges of pack ice in the winter, and mothers bear their young on ice in the spring. As sea ice retreats further from the shore of Chukchi Sea in late summer, walruses have been making dramatic “haulouts” over land, where young walrus are especially vulnerable to being trampled in the rush. An estimated 35,000 walruses clambered onto the coast at Point Lay, Alaska, in September 2014, and thousands more did the same in 2015. At the same time, some of the Arctic’s regional walrus populations have had a chance to rebuild their numbers in recent decades after years of largely unrestricted hunting. Walrus are at no immediate risk of extinction: there are at least 25,000 walruses in the high-latitude Atlantic, with many tens of thousands more in the Pacific. As sea ice continues to suffer, though, the concern is that the negative effects will put an increasing dent in walrus recovery. The Chuckchi Sea is now free of sea ice for about a month each year, but that may rise to several months later in this century.


Figure 3. A female walrus rests beside a yearling during a land-based “haulout” on September 19, 2013. The coastal walrus haulouts that form during periods of sea ice scarcity in the Chukchi Sea are composed primarily of adult female walruses and young, as well as some adult male walruses. Image credit: Ryan Kingsbery, USGS.

The big shift from snow to rain in Western mountains
Several posters examined the ongoing trend across the US West toward more winter rain and mixed-precipitation events and fewer all-snow events. Temperatures during winter and spring have warmed by roughly 2°C over the West since the 1950s. Michael Dettinger (USGS) extended prior work by others showing that most stations across the West are experiencing a larger fraction of their precipitation on days when no snow is reported. One of the best-instrumented locations in the West provides a closer look at this transition. More than three dozen precipitation stations with 55 years of data are scattered across the Reynolds Creek watershed of southwestern Idaho, which covers 93 square kilometers (about three times the size of Manhattan). Elevations vary from about 3000 to 6700 feet, so it’s easy for a winter storm to bring rain to lower elevations and snow to the higher terrain. Looking at the trends over the last three decades (1984 to 2014), Danny Marks (USDA) and colleagues found a doubling of the area in which most winter precipitation events arrived primarily as rain, and a halving of the area in which most of the events were primarily snow.

There will be far more rain than snow next week over the United States east of the Rockies, but one famously snowy city is on the verge of its first accumulation of the winter, which would fall atop green grass (see photo below). Buffalo, NY, received several hours of light snow on Friday afternoon, with a measurable amount possible before the evening is done. Update: Just before 7:00 pm EST Friday, Buffalo finally reported its first measurable snow of the season (0.1", the minimum amount that qualifies as measurable]. Prior to this year, the latest that Buffalo has seen its first 0.1” of snow for the winter was on December 3, 1899.

Steve Gregory has an update today on the long-range outlook beyond the impending holiday warmth. We’ll be back on Monday with a new post. In the meantime, have a great weekend, everyone!

Bob Henson



Climate Change Arctic Winter Weather

November 2015: Earth's Warmest November and 2nd Warmest Month of Any Kind on Record

By: Jeff Masters , 6:23 PM GMT on December 17, 2015

November 2015 was Earth’s warmest November on record by a huge margin, according to data released by NOAA's National Centers for Environmental Information (NCEI) on Thursday. November 2015 also had the second largest positive departure of temperature from average of any month among all 1631 months in the historical record that began in January 1880; only last month (October 2015) was more extreme. As shown in the table below, October and November 2015's 0.97°C and 0.99°C departures from the 20th Century average beat the next eight runners-up by an unusually large margin, underscoring how unusual and extreme the current surge in global temperatures is. NASA also rated November 2015 as the warmest November in the historical record. November 2015's warmth makes the year-to-date period (January - November) the warmest such period on record, according to both NOAA and NASA. November 2015 was the seventh consecutive month a monthly high temperature record has been set in NOAA's database, and the ninth month of the eleven months so far in 2015. The potent El Niño event in the Eastern Pacific that crossed the threshold into the "strong" category in early July continued to intensify into mid-November, and is now slowly waning. Strong El Niño events release a large amount of heat to the atmosphere, typically boosting global temperatures by at least 0.1°C. This extra bump in temperature, when combined with the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, makes it virtually certain that 2015 will be Earth's second consecutive warmest year on record. The lingering warmth from El Niño is likely to make 2016 a good bet to exceed even 2015's warmth.

NOAA's top ten warmest global monthly departures from the 20th Century average:
1) 0.99°C, Oct 2015
2) 0.97°C, Nov 2015
3) 0.91°C, Sep 2015
4) 0.89°C, Mar 2015
5) 0.88°C, Feb 2015
5) 0.88°C, Jan 2007
7) 0.87°C, Aug 2015
7) 0.87°C, Jun 2015
9) 0.86°C, Feb 1998
10) 0.85°C, May 2015


Figure 1. Departure of temperature from average for November 2015, the warmest November for the globe since record keeping began in 1880. Record warmth was observed over the Caribbean, most of equatorial and northeastern South America and parts of southeastern Asia. Parts of the Barents Sea in the Arctic and much of the Indian Ocean were also record warm. Image credit: National Centers for Environmental Information (NCEI) .


Figure 2. Departure of the global surface temperature from average for the year-to-date period January - November, for all years from 1880 to 2015. This year is on pace to easily beat last year as the warmest year on record. Image credit: NOAA.

Global satellite-measured temperatures in November 2015 for the lowest 8 km of the atmosphere were the warmest November readings in the 37-year record, according to the University of Alabama Huntsville (UAH). This is the second consecutive month the UAH database has registered a record monthly high. The lowest 8 km of the atmosphere heats up dramatically in response to moderate to strong El Niño events, with a time lag of about six months.



Two billion-dollar weather disasters in November 2015
Two billion-dollar weather-related disasters hit the Earth last month, according to the November 2015 Catastrophe Report from insurance broker Aon Benfield: severe monsoon flooding in South India and Sri Lanka that killed 328 people and did $3 billion in damage, and intense drought in South Africa that has cost at least $2 billion. With 24 billion-dollar weather disasters so far in 2015, Earth is on pace for a below-average number of these disasters, compared to the average of 28 recorded during the previous 10-year period, 2005 - 2014.


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


Disaster 2. One of the worst droughts in decades intensified in South Africa during November 2015. Some of the hardest-hit areas included KwaZulu-Natal, Mpumalanga and Limpopo provinces. Water shortages affected 2.7 million households, agricultural production plummeted, and economic damages were estimated at $2 billion. In this image, we see the carcass of a dead cow in the Black Umfolozi River, in Nongoma district north west from Durban, South Africa on November 9, 2015. Image credit: MUJAHID SAFODIEN/AFP/Getty Images.

Arctic sea ice comes in at 6th lowest November extent on record
Arctic sea ice extent during November 2015 was the 6th lowest in the 36-year satellite record, according to the National Snow and Ice Data Center (NSIDC).

Notable global heat and cold marks set for November 2015
Hottest temperature in the Northern Hemisphere: 42.3°C (108.1°F) at Matam, Senegal, November 6.
Coldest temperature in the Northern Hemisphere: -54.2°C (-65.6°F) at Geo Summit, Greenland, November 4.
Hottest temperature in the Southern Hemisphere: 46.8°C (116.2°F) at Dampier, Australia, November 15.
Coldest temperature in the Southern Hemisphere: -61.1°C (-78.0°F) at Concordia, Antarctica, November 1.

Major stations that set (not tied) new all-time heat or cold records (for any month) in November 2015
Saint Laurent do Moroni (French Guiana, France) max. 37.9°C, November 3:  New Territorial record high for French Guiana
Pirapora (Brazil) max. 41.2°C, November 6
Montes Claros (Brazil) max. 40.3°C, November 6
Barra (Brazil) max. 40.0°C, November 6
Januaria (Brazil) max. 41.4°C, November 7
Middle Point (Australia) max. 41.6°C, November 8
Pretoria Unisa (South Africa) max. 40.3°C,  November 11
Johannesburg (South Africa) max. 36.5°C,  November 11
Frankfort (South Africa) max. 36.9°C, November 11
Oudestad (South Africa) max. 40.8°C, November 11
Estcourt (South Africa) max. 39.6°C, November 11
Towoomba (South Africa) max. 42.4°C, November 11
Gabarone Airport (Botswana) max. 41.5°C, November 11
Ladysmith (South Africa) max. 40.7°C, November 11
Bulawayo Airport (Zimbabwe) max. 38.6°C,  November 12
Gokwe (Zimbabwe) max. 38.2°C, November 13
Januaria (Brazil) max. 41.5°C,  November 13
Maumere (Indonesia) max. 36.6°C,  November 13;  increased to 36.9°C on November 30
Ampenan (Indonesia) max. 36.6°C,  November 22
Cipo (Brazil) max. 42.0°C, November 26



New all-time national and territorial heat records set or tied in 2015
As of December 15, 2015, sixteen nations or territories tied or set all-time records for their hottest temperature in recorded history in 2015, and two (Israel and Cyprus) set all-time cold temperature records. For comparison, only two nations or territories set all-time heat records in 2014, and nine did in 2013. The most all-time national heat records held by any year is nineteen in 2010. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. I use as my source for international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Wunderground's weather historian Christopher C. Burt maintains a database of these national heat and cold records for 235 nations and territories on wunderground.com's extremes page.

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

Bob Henson and I will appear on WU’s live show, “This Week in Weather”, at 5 p.m.ET/2 p.m. PT today (Thursday) as we highlight some of the major weather stories of the year.  To watch, go to http://www.wunderground.com/live-forecasts"

Jeff Masters

Climate Summaries

The Top Ten Reasons to be Hopeful on Climate Change

By: Jeff Masters , 5:57 AM GMT on December 16, 2015

Bob Henson and I are in San Francisco this week for the annual meeting of the American Geophysical Union (AGU), the world’s largest climate science conference. Over five thousand of the world’s top climate scientists are here, giving a staggering 10,000 talks and poster presentations. It’s total information overload, and Bob and I will only be able to offer a small sample of the incredible amount of science being presented here.

My favorite talk today: “Barrier Busting: Leapfrogging Zombie Science Arguments to Get to Solutions," by my favorite communications expert, Susan Hassol of climatecommunication.org. She argued that emphasizing the solutions to climate change rather than talking about the science, is a better way to communicate to the public. Talking about the science of climate change often leads to confusion, due to long-discredited arguments by climate change deniers that rise from the dead like zombies. But people are very supportive of actions to take action on climate change, regardless of their views on the science. For example, 72% of Republicans and 68% of conservative Republicans support efforts to develop clean energy, even though far fewer than half of them believe that the climate is warming and humans are responsible.

Susan presented her top list of reasons to be hopeful about climate change:

10) President Obama has put climate change at the top of his agenda.

9) The Pope has framed climate change as a moral issue.

8) China has become highly motivated and engaged, and naysayers can no longer claim that we shouldn’t do anything because China is not.

7) Emissions and the economy are decoupling: for the first time, we had a year where the economy grew, but emissions of greenhouse gases did not.

6) The cost of solar power is falling fast.

5) Solar energy capacity is growing rapidly.

4) Wind energy capacity is growing rapidly.

3) Half of all new power resources coming on-line globally are in renewable energy, and that percentage is near 70% in the U.S.

2) Businesses are engaging in promoting climate change action.

1) The Paris Accord! The nations of the world have now dedicated themselves to decarbonizing the world economy.

Climate change solution resources
Susan recommended four websites with resources that help people understand potential solutions to climate change issues (all are all linked at https://www.climatecommunication.org/resources/#websites):

1) Climate Interactive, which develops simplified yet scientifically rigorous models that can help people see the climate impacts of various policy choices and emissions pathways.

2) The Solutions Project, which lays out how we can accelerate the transition to 100% clean renewable energy. They’ve created renewable energy plans for all 50 U.S. states and many countries.

3) The Deep Decarbonization Pathways Project, a global collaboration of energy research teams across 16 countries that charts practical pathways to deeply reducing greenhouse gas emissions.

4) Energy Innovation, which seeks to accelerate progress on clean energy by identifying and supporting policies that most effectively reduce greenhouse gas emissions using research and analysis.



Video 1. Emphasizing the solutions to climate change rather than talking about the science is a better way to communicate to the public on the subject, argues my favorite communications expert, Susan Hassol of climatecommunication.org, in her 2015 TEDx talk “ClimateTalk: Science and Solutions.”

Jeff Masters


Climate Change

Historic Paris Climate Deal: A Low Va Va Voom

By: Bob Henson and Jeff Masters , 5:29 PM GMT on December 14, 2015

After two weeks of intricate negotiation, world leaders wrapped up the 2015 UN climate summit in Paris with the most important diplomatic advance on global climate protection in more than two decades. The end product was the Paris Agreement (see PDF), a finely tuned document aimed at getting all of the world’s nations on board with plans to reduce greenhouse gas emissions--even if those plans are not legally binding.


Figure 1. Executive Secretary of the United Nations Framework Convention on Climate Change (UNFCCC) Christiana Figueres, Secretary General of the United Nations Ban Ki Moon and Foreign Affairs Minister and President-designate of COP21 Laurent Fabius raise hands together after adoption of a historic global warming pact at the COP21 Climate Conference in Le Bourget, north of Paris, on December 12, 2015. Envoys from 195 nations adopted the historic accord. Image credit: Francois Guillot/AFP/Getty Images.


Key parts of the Paris Agreement include:

--New global targets. The Paris Agreement emphasizes the importance of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C.” The 1.5°C goal was originally proposed years ago by small island states for which any greater warming could spell extinction. In a surprise move, the U.S., European Union, Brazil, and many other nations joined forces with those small island states to argue on behalf of including the 1.5°C goal. For now, the target is mainly a statement of solidarity and empathy, given that the nation-by-nation plans submitted over the last few months would together limit global warming to perhaps 2.7°C over preindustrial levels at best.

--Regular review and fine-tuning. The targets in each national plan will remain voluntary--largely out of deference to the U.S. Congress, which telegraphed its refusal to approve binding U.S. targets. But the Paris Agreement does include newly binding requirements on how each nation reports progress toward its targets, to help ensure accountability on the world stage. The plans must be reviewed and revised every five years, with an eye toward greater emission cuts over time as renewable technologies are deployed at larger scale.

It appears that the legally binding requirements of the Paris Agreement may not require approval from the U.S. Congress if they are interpreted as extensions of the UN Framework Convention on Climate Change, which was signed by President George H.W. Bush and approved by the U.S. Senate in 1992.

Was the Paris summit a success?
The international nonprofit group E3G had envisioned three possible outcomes from Paris:

Le Zombie--tactical deal with high potential for collapse
Comme ci, Comme ça’--modest progress with guarantees on finance
Va Va Voom--cements a new enduring regime on climate change

E3G rated the final result as a “low Va Va Voom.” According to E3G, the Paris Agreement “signals the end of business as usual for the energy industries. Future investment will need to be compatible with a zero carbon world.” The agreement is also expected to hasten other activity on the regional, state, and local scales worldwide. For example, mayors from hundreds of cities around the world pledged in Paris to move toward a year-2050 target of 100% renewable energy or an 80% reduction in greenhouse gases.

Will it be enough?
This year’s global temperature is likely to reach 1.0°C above preindustrial levels. It’s been estimated that the known global reserves of fossil fuel are already several times more than enough to push us above the 2.0°C target. In the wake of the Paris Agreement, some activists and policymakers argue that good intentions and voluntary targets could still wilt in the face of economic pressure to use this coal, oil, and gas. The eminent climate scientist James Hansen, now retired from NASA, called the Paris talks “a fraud,” arguing that a fee on emitting carbon remains essential: “As long as fossil fuels appear to be the cheapest fuels out there, they will be continued to be burned.”

There are several ways to use market forces to reduce greenhouse emissions, including a tax or fee on carbon as well as cap-and-trade mechanisms. Many nations, regions, and states have adopted cap-and-trade systems, including the northeast U.S., and Climate Central’s John Upton recently showed how interstate collaboration may help reduce emissions from U.S. power plants under new EPA guidelines. We can expect a further blossoming of such arrangements as nations around the world explore ways to meet their Paris commitments. Yet this won’t be a cake walk, as veteran climate writer and activist Bill McKibben pointed out in a Guardian essay on Sunday, using the apt analogy of a marathon: “Our only hope is to decisively pick up the pace...We know where we’re going now; no one can doubt that the fossil fuel age has finally begun to wane, and that the sun is now shining on, well, solar. But the question, the only important question, is: how fast.”


Figure 2. Typhoon Melor as seen by Japan’s Himawari satellite at 0237Z Monday, December 14 (9:37 pm EST December 13), 2015. At the time, Melor was a Category 3 storm with 125 mph winds, and the southern eyewall of the storm was over northern Samar Island. Image credit: NOAA/RAMMB.

Yet another Category 4 in the Pacific: Melor churns through Philippines
Typhoon Melor powered into the Central Philippines on Sunday night, December 13 (U.S. EST time) as a Category 3 storm with 125 mph winds. This was slightly below its peak intensity as a Category 4 storm with 135 mph winds at 8 am EST Sunday, when Melor became the record-smashing 26th Northern Hemisphere Category 4 or stronger storm this year (previous record: just 18 such storms in 1997 and 2004, according to WU contributor Dr. Phil Klotzbach.) Melor is also the 20th typhoon of 2015, which is the most typhoons in the Northwest Pacific since 2004 (which also had 20 typhoons.) Melor is the strongest December typhoon to affect the Philippines since Typhoon Bopha of 2012, which hit Mindanao Island on December 3 as a Category 5 storm with 175 mph winds.

Damage is likely to be heavy from Melor, since the southern eyewall of the storm tracked along the north coast of Samar Island for several hours when the typhoon was at Category 3 strength. The Philippine Meteorological agency, PAGASA, warned that Melor could bring a storm surge as high as 4 meters to the coast, and rainfall amounts of 10+ inches were expected over a wide swath of the Philippines along Melor’s path. As it weakens, Melor is expected to make a final Philippines landfall on Mindoro Island on Tuesday morning local time.


Figure 3. A view of the powerful extratropical cyclone over the Bering Sea from Japan’s Himawari satellite at 0500Z Sunday, December 13, 2015. Image credit: NOAA/RAMMB.

Aleutians pummeled by fierce cyclone in Bering Sea
Melor wasn’t the only cyclone thrashing around the North Pacific this past weekend. An extremely strong non-tropical low developed south of the Aleutian Islands and raced north, deepening to a central pressure estimated by the Ocean Prediction Center at 06Z Sunday as 924 millibars. According to WU weather historian Christopher Burt, this ranks with the Bering Sea storm from November 7-8, 2014, and another one from October 25, 1977, as the strongest extratropical lows observed in the North Pacific since reliable records began in late 1969. Both of those two previous systems developed from the remnant circulations of typhoons, a common source of Aleutian storms that was not in play last weekend. A drifting buoy northeast of Adak--the westernmost town in the United States--reported a pressure of 929 mb, and sustained winds at Adak reportedly reached at least 94 mph. If confirmed, these would be the highest sustained winds on record for Alaska.

We’ll be back by Wednesday at the latest with a report from the American Geophysical Union Fall Meeting in San Francisco.

Bob Henson (Paris Agreement, Bering Sea storm), Jeff Masters (Typhoon Melor)



Climate Change Politics Climate Change Hurricane Extreme Weather

Tornadoes, Record Downpours Possible This Weekend Over Parts of Plains

By: Bob Henson , 4:50 PM GMT on December 11, 2015

Residents of Oklahoma and Texas may need to watch the skies en route to holiday shopping or partying on Saturday, as a severe weather outbreak is possible. A powerful upper-level jet stream bearing winds of more than 170 mph (see Figure 1) is slamming into the West Coast this morning and will carve out a sharp trough over the Southern Plains on Saturday. Very warm air is already in place--record or near-record highs in the upper 70s and low 80s are expected on Friday over western Oklahoma and Texas--and the approaching trough will lead to a rapid return of rich Gulf moisture by Saturday. In its Day 2 forecast issued Friday morning, NOAA’s Storm Prediction Center called for a a slight risk of severe weather on Saturday (see Figure 1). Instability could be meager if thick clouds end up cutting back on sunshine. Yet even the modestly unstable air typical of this time of year can be enough for tornadic storms when a potent upper-level storm brings strong vertical wind shear, which helps foster thunderstorm rotation.

Even if tornadic supercells fail to develop, a nighttime squall line with heavy rain and high wind is a fairly good bet. This is already the wettest year on record for Dallas-Fort Worth, where only 1.22” is needed to reach the 60-inch mark. Values of precipitable water (the amount of water vapor available in the atmosphere) may set record highs for December from the Southern Plains into the Midwest. Rains of 2” - 4” or more will be widespread toward Arkansas and Louisiana by Sunday as the squall line sweeps east. A second focus of very heavy rain (2” or more) will extend from Iowa into Wisconsin, where downpours are rare in December. Some locations in the Midwest could rack up monthly records for their heaviest 1- or 2-day rains. However, SPC is only predicting a marginal risk of severe weather on Sunday due to extensive cloudiness and rain-cooled air.


Figure 1. The Day 2 convective outlook produced by NOAA’s Storm Prediction Center, issued at 0555Z Friday, December 11, 2015 (11:55 pm CST Thursday), and valid on Saturday.


Figure 2. WunderMap depiction of wind speeds (in knots) at 200 mb (about 30,000 feet) predicted by the 06Z Friday run of the GFS model for 6 pm CST Saturday evening, December 12, 2015.


Figure 3. Rainfall projected from 12Z (6:00 am CDT) Friday, December 11, 2015, through 12Z Monday, December 14. Image credit: NWS Weather Prediction Center.

Oklahoma’s history of holiday twisters
A surprising number of tornadoes have targeted Oklahoma during the final month of the year. For the official period of record, starting in 1950, the state has seen a total of 25 tornadoes during December. The most injurious of the bunch was on December 5, 1975, when 38 people were hurt by an F3 tornado that caused extensive damage in northeast Tulsa. (Here’s a Tulsa World gallery with some excellent archival photos.) On Christmas Eve morning of 1982, a pair of twisters injured 17 people, again in the Tulsa area, and on New Year’s Eve 2010, a tornado ripped across a 21-mile path from northeast Oklahoma into northwest Arkansas.

Rare December tornado hits the Columbia Valley of Washington
The upper-level storm heading for Oklahoma has already led to some tornadic trouble. Three dozen homes were damaged late Thursday morning by an EF1 tornado that moved through the Washington town of Battle Ground, just north of the Columbia River, with winds topping 100 mph. Washington and Oregon each average a couple of tornadoes per year, scattered across the calendar. Nearly all are rated F/EF0 or F/EF1 on the Fujita scale. According to the Tornado History Project, the Battle Ground twister was the state’s fifth on record for the month of December since 1950. No serious injuries or fatalities were reported, which keeps the nation on track for what could be its lowest annual tornado death toll in at least 141 years.

Coming soon: the latest science from AGU and the outcome from Paris
Jeff Masters and I will be covering the American Geophysical Union’s 48th Fall Meeting in San Francisco next week. We’ll also report on the landmark global climate agreement that’s expected to be finalized late Friday or Saturday in Paris. The Guardian’s live blog is producing hour-by-hour live-blog coverage of the negotiations and related protests.

Have a great weekend, everyone!

Bob Henson




Severe Weather Tornado Extreme Weather

First Look at 2016 Hurricane Season: Unusually Big Question Marks

By: Bob Henson , 7:51 PM GMT on December 10, 2015

Even more than one might expect, the 2016 Atlantic hurricane season is shaping up with both high- and low-end possibilities, based on preliminary thoughts released Thursday by a team at Colorado State University. The CSU project, founded by Dr. William Gray with Dr. Phil Klotzbach now serving as lead author, has issued seasonal outlooks since 1984 for the anticipated amount of hurricane activity in the Atlantic basin. In 1993 the group began issuing outlooks each December for the following year’s activity, but in 2011 those outlooks were dropped due to lack of any demonstrated skill. In its place, the CSU team now releases what they call a “qualitative discussion,” which highlights the factors at play and includes a more generalized sense of what we might expect.

Although it’s not presented as a quantitive outlook, the Thursday release (PDF) does include a set of four potential scenarios for 2016, each rated in terms of probabilities that we will see a given amount of seasonally-averaged accumulated cyclone energy (ACE). These scenarios hinge on two factors: how quickly the current El Niño will diminish, and how the Atlantic Multidecadal Oscillation/thermohaline circulation (AMO/THC) will evolve.

1. AMO/THC becomes above average in 2016 and no El Niño impacts remain (resulting in an ACE of ~ 170) – 25% chance
2. AMO/THC is above average in 2016 but some El Niño impacts remain (ACE ~ 120) – 35% chance
3. AMO/THC is below average and no El Niño impacts remain (ACE ~ 80) – 20% chance
4. AMO/THC is below average and some El Niño impacts remain (ACE ~ 50) – 20% chance

CSU relates the ACE values shown above to these general ranges of activity:

170 ACE – 14-17 named storms, 9-11 hurricanes, 4-5 major hurricanes
120 ACE – 12-15 named storms, 6-8 hurricanes, 2-3 major hurricanes
80 ACE – 8-11 named storms, 3-5 hurricanes, 1-2 major hurricanes
50 ACE – 5-7 named storms, 2-3 hurricanes, 0-1 major hurricane

The upshot is that we have a 45% chance of falling into one of the two more extreme scenarios: either #1 (a very busy season) or #4 (a very quiet season). Looking back at each of the last four years, CSU placed the combined odds of the highest- and lowest-end scenarios at only 20% to 25%. So if CSU is right, the Atlantic season of 2016 has an considerably better chance than the last four seasons of being either unusually active or uncommonly tranquil. Want more evidence for this split verdict? CSU points out the wildly contrasting outcomes for the Atlantic hurricane seasons that followed our two other “super El Niño” events since 1950 (1982-83 and 1997-98):

1983: Atlantic ACE = 17% of average
1998: Atlantic ACE = 182% of average

This stark difference is largely because the 1982-83 El Niño decayed gradually, holding on till midsummer, whereas the 1997-88 El Niño quickly shifted into a moderate La Niña by late summer. The most recent monthly outlook for El Niño, issued Thursday by NOAA, calls for a transition to ENSO-neutral conditions by late spring or early summer. Computer models are in agreement on this shift, though the timing varies somewhat. More often than not, a strong or very strong El Niño event is followed by La Niña in the next summer or autumn. It’s certainly possible that La Niña could be in place by late summer (see Figure 1 below), which would favor an active Atlantic hurricane season.


Figure 1. The December outlook issued by a collaborative group of forecasters at NOAA’s Climate Prediction Center and the International Research Institute for Climate and Society (IRI). The odds of neutral or La Niña conditions rise considerably by next summer. Image credit: NOAA/IRI.

How do El Niño and the AMO/TCH influence hurricanes?
In a relationship that’s well understood, El Niño tends to suppress Atlantic hurricane activity, mainly by enhancing upper-level wind shear, while La Niña favors more Atlantic activity by reducing wind shear. These factors come and go from year to year. Meanwhile, the ups and downs of the AMO/THC modulate hurricane activity over much longer periods by affecting sea-surface temperatures and other conditions over the tropical and subtropical Atlantic. “These changes are natural and have been occurring for at least the last 1,000 years,” notes a NOAA FAQ on the phenomenon.

The AMO/THC has shown large multidecadal trends over the last century, favoring reduced hurricane activity from the 1970s to the mid-1990s and increased activity from that point until the early 2010s. Over the last couple of years, the AMO/THC has slowed down, in tandem with a reduction in Atlantic hurricane activity. However, the AMO/THC can vary on the shorter term as well, so it’s not yet certain that we have entered a new multi-decade era of reduced activity--although Phil Klotzbach made the case for this in a paper published in Science this past September and summarized in a writeup by Klotzbach at Capital Weather Gang. (The Science paper can be accessed through a link at the bottom of the CWG article.) Even if we are indeed in a new era, shorter-term factors could strengthen the AMO/THC during a given year. This includes the train of weather features and oceanic effects that El Niño is expected to produce over the next few months from the Pacific to the Atlantic.

“The uncertainties related to the AMO for 2016 are enormous,” said Eric Blake (National Hurricane Center) in an email, “because we lack a reliable way to track the feature and because of possible effects of El Niño countering the longer-term cycle.”

CSU will issue its full seasonal outlooks for Atlantic hurricane activity in 2016 on April 14, June 1, and August 3. As one would expect, the skill of these outlooks steadily improves as the hurricane season nears. Even if it’s too soon right now to expect an accurate forecast for 2016, the latest thoughts from CSU make me even more eager to see how this very uncertain hurricane season will unfold.

Bob Henson


Figure 2. The largest patch of below-average ocean temperatures for 2015 (January - October) has been in the North Atlantic, where record-cold values have been observed southeast of Greenland. These values are consistent with a weaker Atlantic multidecadal oscillation/thermohaline circulation. Image credit: NOAA/NCEI.


Hurricane

After Warmest Autumn on Record, December Mildness Sweeps Across U.S.

By: Bob Henson , 7:36 PM GMT on December 09, 2015

Meteorological autumn (September – November) was the warmest in 121 years of recordkeeping for the 48 contiguous U.S. states, according to NOAA’s national wrapup of November and fall conditions released Wednesday morning. The national average of 56.8°F was a full 3.3°F above the 20th-century average and 0.2°F above the previous record of 56.6°F (Sep-Nov 1963). Only one state (Florida) had its warmest autumn on record, but the nation as a whole still came out on top because of the rare coast-to-coast nature of the warmth. Often, one part of the country will have a mild three-month period while another part is colder than average, as we saw dramatically this past winter with record warmth in the West and unusual chill in the East.

This past autumn was also fairly damp on a national scale, with the 48 states recording their 15th wettest autumn. November came in on the mild and wet side for the contiguous U.S., ranking as the 13th warmest and 15th wettest November since records began in 1895.


Figure 1. Temperature ranks for each of the 48 contiguous U.S. states during autumn 2015 (September through November). Higher numbers indicate warmer readings. Florida had its warmest autumn on record (#121 out of 121 years). Image credit: NOAA National Centers for Environmental Information

The large-scale mildness hasn’t abated, as temperatures were well above freezing Wednesday morning over nearly all of the United States east of the Rockies. None of the nation's regular reporting stations in the contiguous 48 states--including mountain locations--managed to get below 10°F on Tuesday, according to Nick Wiltgen at weather.com. (By comparison, each day in December 2013 saw at least one sub-0°F reading in the Lower 48.) All this is leading into what looks like a unusually long stretch of very mild weather for mid-December. Even Canada’s largest city, Toronto, might avoid any temperatures below freezing for at least the next week, based on the Weather Underground city forecast issued at midday Wednesday. The imminent, widespread “warm wave” over eastern North America was anticipated a month ago by long-range forecast models and is consistent with the typical December effects of a strong El Niño.


Figure 2. Snow depth analyzed on December 9, 2015. Image credit: NOAA/NWS National Operational Hydrologic Remote Sensing Center.


Northeast: Where’s the snow?
Large parts of New York and New England, including most major cities, have yet to receive any measurable snow this autumn, and some areas could easily make it to the winter solstice snow-free. Measurable snow is defined as an accumulation of at least 0.1”, as measured on a snowboard; any lesser amount is classified as a “trace” of snow. Buffalo, New York, is racing past its previous lateness record for the first measurable snow of the season (Dec. 3, 1899). Albany, NY, is also waiting for its first measurable snow, but the city has gone as late as Christmas Eve before getting its first snow (Dec. 24, 1912). Even snow-loving Burlington, VT, which averaged 81” per winter between 1981 and 2010, has only received 0.2” thus far, with nothing more in the current forecast. Burlington has gone as late as Dec. 21, 1948, before seeing its first inch of snow on the ground. This autumn’s delay is especially remarkable given that the first three months of 2015 were the coldest Jan-Mar period on record for both New York and Vermont!

The dynamics associated with El Niño are likely to keep unusually mild weather predominating over the northern U.S. for most of the winter, according to seasonal outlooks from the National Weather Service. Some forecasters are pointing to signals that appear to favor development of a negative North Atlantic Oscillation by January. Negative NAO conditions during El Niño can enhance the odds of one or more snowy nor’easters over the mid-Atlantic and New England. Among those calling out the negative NAO risk is the team at Atmospheric Environment Research led by Judah Cohen. This group has related the advance of October snow cover in Siberia to the likelihood of atmospheric energy propagating upward the stratosphere and fostering a disruption of the polar vortex months later. However, in its latest outlook, issued on Monday, AER included a strong caveat: “The key will be how strong the energy transfer from the troposphere to the stratosphere is in late December and how much the polar vortex is perturbed. If the energy transfer does not significantly weaken the polar vortex, the AO will likely remain mostly positive and mild temperatures will dominate the mid-latitudes.”


Figure 3. A compromised U.S. Highway 12 west of White Pass, Washington, on Wednesday morning, December 9, 2015. White Pass is located in the Cascades just south of Mount Rainier. A 58-mile stretch of U.S. Highway 12 is now closed between Packwood and Naches. Image credit: Washington State Department of Transportation.

Pacific Northwest: pummeled by wet, wild storms
A freight train of high-energy, moisture-laden Pacific storms has crashed into Washington and Oregon over the last week, causing widespread flood and wind damage and putting many roads (and weather records) under water. In Washington, three-day rainfall totals have topped 10” at some sites, and wind gusts of 40-60 mph or more have been common, with a mesonet station at White Pass reporting a gust to 99 mph on Tuesday. Both Seattle and Portland pulled off impressive hat tricks on Tuesday, setting daily records for both warmest low and warmest high temperature as well as rainfall:

Seattle: low 50°F, high 60°F, rainfall 2.13”
Portland: low 56°F, high 62°F, rainfall 1.67”

It’s not only been warm, wet, and windy, but also very dark. On Monday, the amount of solar energy penetrating through the clouds over Seattle was the least for any date in almost nine years, according to Mark Albright and Cliff Mass (University of Washington).


Figure 4. A channel of high precipitable water (blue ribbon) extended from the tropics into the Pacific Northwest on Wednesday morning, December 9, 2015. Precipitable water is the amount of rain that would fall if all of the water vapor in the atmosphere above a given point were suddenly squeezed out. Image credit: ClimateReanalyzer.org/University of Maine.


The extreme rainfall in the Pacific Northwest, together with record warmth in spite of thick clouds, points to the tropical origins of the air streaming that way. The upper-level energy behind these storms has been rolling in mainly from the west, carried by an extremely strong Pacific jet stream, but the storms themselves have tapped into deep tropical moisture south of Hawaii--a classic source region for “Pineapple Express” storms. The Pineapple Express is one type of atmospheric river, a channel of moisture typically 300-400 miles wide that flows from the tropics into midlatitude storm systems. As much as half of all precipitation on the U.S. West Coast each year comes from just a few atmospheric rivers. Typically during a strong El Niño, atmospheric river events shift southward into California during January and February.

The big storms in the Pacific Northwest are serving as perfect research material for OLYMPEX. This NASA-supported field experiment designed to verify and validate the satellite-based rainfall and snowfall measurements produced by the international Global Precipitation Measurement (GPM) program, including the core GPM satellite launched in 2014. OLYMPEX will continue through February.


Figure 5. Residents make their way through flood waters on December 7, 2015 in Carlisle, England. Image credit: Jeff J Mitchell/Getty Images

Huge storms slam into Iceland, United Kingdom
Another well-defined channel of moisture, extending all the way from the Caribbean into the far northeast Atlantic (see Figure 6 below), has fueled a series of intense storms across Iceland and the British Isles over the last several days. The heaviest 24-hour rainfall in U.K. weather history occurred over the weekend, with an amazing 341.4mm (13.44”) reported at Honister Pass in northwest England. Devastating flooding occurred across England’s Lake District, with damages from the storm estimated to be at least £500 million (about $750 million U.S.). The focus shifted westward early this week with another upper-level storm and intense surface low, this time centered near Iceland. It was reportedly the nation’s worst storm in more than 20 years, with extensive property damage. Wind gusts of 125 mph were reported in hourly data from Hallormsstaðaháls, and news reports indicate that gusts may have reached 162 mph on Monday night (thanks to Stu Ostro and Jon Erdman for these reports).

We’ll be back with a new post on Thursday. Steve Gregory has more on the eastern warmth and western storminess in his latest WU post.

Bob Henson


Figure 6. Water vapor streams from the Caribbean northeastward to the British Isles in this satellite image from 20Z (4:00 pm EST) Friday, December 4, 2015. Image credit: UW-Madison SSEC RealEarth, courtesy Stu Ostro, The Weather Channel.


Climate Summaries Extreme Weather Flood

El Niño’s Role in Deadly Chennai Rains; Progress in Paris Climate Talks

By: Bob Henson , 4:02 PM GMT on December 07, 2015

Conditions in far southeast India are slowly improving after five weeks of frequent torrential rain that has led to more than 250 deaths. A region of low pressure positioned near Sri Lanka during much of the period channeled moisture from the Bay of Bengal and the record-warm eastern Indian Ocean toward the region. Much of the suffering has been in Chennai, an urban area of more than 9 million people that ranks as the largest in South India and among the world’s 40 largest metro areas. Parts of Chennai have spent days inundated by as much as eight feet of polluted water, with widespread power outages exacerbating the crisis. At least 18 patients died in a Chennai intensive-care unit after backup power to ventilators was knocked out. Last month Chennai recorded 1218.6 mm (47.98”) of rain, the highest observed for any November in more than 100 years of recordkeeping. Then, on December 1-2, a total of 345 mm (13.58”) fell in 24 hours, which smashed the city’s all-time 24-hour record rainfall of 261.6 mm on December 10, 1901. Estimated losses in the region have already topped $2 billion US.


Figure 1. People wade through a flooded street in Chennai, in the southern Indian state of Tamil Nadu, on Wednesday, December 2, 2015. Image credit: AP.

Along with the heavy rains, the Indian Express cited infrastructure issues as a key part of the disaster: “While officials at the India Meteorological Department have said the exceptionally strong El Niño, along with a rare ‘coincidence of various factors’, has resulted in the heavy rain, there’s no denying that Chennai has failed in maintaining an effective storm water drainage system.” At Slate, Eric Holthaus reviewed how fast-growing industrialization made matters worse in Chennai: “For a city built on a floodplain, development has essentially gone unchecked: Critical infrastructure--like the airport, automobile manufacturing plants, and IT centers as well as countless houses--has been built over streams and marshes, and plastic bags clog drainage networks.”

Holthaus also noted the well-established relationship between warming global temperatures and the intensification of short-term rainfall events, which has been observed in many parts of the globe. This effect appears especially strong in the tropics, according to a study published earlier this year in the journal Current Climate Change Reports by Paul O’Gorman (Massachusetts Institute of Technology).


Figure 2. Chennai’s airport was closed for four days last week, with some 4000 people and dozens of aircraft stranded. At one point, all runways were under water. This photo is from Thursday, December 2, 2015. Image credit: Atul Yadav/ Press Trust of India via AP.

El Niño’s contrasting effects on the Indian monsoon
Cyclic, large-scale oceanic and atmospheric features--including El Niño--helped set the stage for the South India disaster. El Niño has a dual effect on monsoonal rains across India, hinging on the two phases of the monsoon itself. By far the biggest player in India’s climate is the summer, or southwest, monsoon, in which moist air sweeps across the nation from southwest to northeast during the late spring and summer. The phenomenon’s alter ego is the winter, or northeast, monsoon, in which northeast winds push back across the nation during autumn and winter. For most of the nation, the northeast monsoon has a drying effect, since the winds are bringing cool, dry air from interior Asia. But as the northeasterlies pass over the Bay of Bengal during autumn, they pick up moisture that is often deposited across far southeast India. Chennai typically receives more than half its moisture this way, with rainfall averaging around 11” in October, 16” in November, and 7” in December. (Chennai’s annual average is around 55”).

El Niño tends to reduce rainfall during the southwest monsoon, as was the case this year, but it also raises the odds of heavy rainfall during the northeast monsoon. The latter effect doesn’t get as much attention, in part because the southwest monsoon is the one that affects the bulk of India. On a global scale, the northeast-monsoon effect in India is small enough that it often gets omitted from maps showing how El Niño affects regional climate. However, it still affects a huge number of people: the population of Tamil Nadu state alone (where the northeast monsoon is the dominant one) is 72 million. Moreover, year-to-year variability is higher for India’s northeast monsoon than it is for the southwest monsoon.

Another player: the Indian Ocean Dipole
Another factor lined up this autumn for a strong northeast monsoon is the Indian Ocean Dipole. During the positive phase of the IOD, warmer-than-average waters extend across the central and western tropical Indian Ocean, with cooler-than-average waters toward the eastern tropical Indian Ocean. A 2004 study by R.H. Kripalani and Pankaj Kumar (Indian Institute of Tropical Meteorology) was one of the first to relate the Indian Ocean Dipole to the strength of the northeast monsoon. It found that a positive IOD was associated with heavier northeast monsoonal rains in South India.


Figure 3. State of the Indian Ocean Dipole, 1982 - present. Crosshatches show monthly readings; the red and blue graph is a three-month running average. Image credit: NOAA Ocean Observations Panel for Climate

The IOD is currently in a strongly positive mode (see Figure 3). Based on NOAA data, the three-month running average this autumn has been in the +0.8°C to +1.0°C range, which ranks among the top five positive IOD events in the last 30 years. So between the IOD and El Niño, two major factors have been in place for unusually heavy rains in and near Chennai this autumn. India’s seasonal forecasters were on top of this risk. In its northeast monsoon outlook issued on October 16, the India Meteorological Department gave 88% odds for a wetter-than-normal monsoon over the South India peninsula, with 90% odds for Tamil Nadu, the state where Chennai is located.

In South Florida, a December deluge
South Florida--another place where El Niño tends to boost cool-season rainfall—has slogged through some of its heaviest December rains on record over the last several days. Miami Executive Airport picked up 8.92” in 24 hours, with 10.11” observed at The Hammocks. For the first six days of the month, Miami International Airport received 8.48”. With more than three weeks to go, this total already beats any December in 104 years of official Miami recordkeeping, with just two exceptions: 12.08” in 1905 and 9.03” in 1929. The first six days of December were wetter than any other week in Miami’s weather history during meteorological winter (December through February), as noted by NHC’s Eric Blake. Although the heaviest rains from Thursday through Saturday targeted the Miami area, South Florida as a whole averaged more than 2”, according to the South Florida Water Management District.


Figure 4. Demonstrators participate in a climate march on Sunday, December 6, 2015 in the coastal city of Oostende, Belgium. Image credit: Nicolas Maeterlinck/AFP/Getty Images.

Draft climate agreement hammered out in Paris
The first half of the two-week UN climate summit in Paris ended on a relatively high note, with a draft agreement delivered on time. The agreement is still peppered with hundreds of bracketed words and phrases, indicating fine and not-so-fine points that need to be worked out over the next week.


Figure 5. Mayors from cities around the world convene at the Paris city hall on Friday, December 04, 2015, for an event called Cities for Climate. Roughly a thousand mayors gathered to coordinate their own efforts to reduce greenhouse emissions. The mayors signed an agreement to work toward 100% renewable energy in their cities, or an 80% reduction in greenhouse gases, by 2050. Image credit: Thierry Chesnot/Getty Images.

This week the negotiation process shifts from diplomats to high-level government ministers from each UN member. These ministers will sign off on the final agreement, including not only the stipulated terms but which ones (if any) are considered legally binding. The latter point is heavily influenced by the United States, since the U.S. Congress has already made it clear it will not approve any legally binding agreement. More likely to emerge is some type of requirement for transparency and regular progress reports from each nation, which would employ international peer pressure rather than legal muscle. One climate policy expert interviewed by AP likened this to playing a soccer game without a referee: “Everything happens in the open in the stadium….So if someone fouls another player, even if he doesn't get a red card, he will be booed by the audience.” Another key aspect to be determined is whether the final draft will refer to a goal of keeping global temperature at no more than 1.5°C above preindustrial levels, a far more challenging goal than even the oft-cited 2.0°C goal. As the draft global agreement evolves, a group of 11 legal experts (including two representatives from each UN region, plus one representative from small-island developing states) will be scrutinizing it for legal and linguistic clarity and consistency.

We’ll have more details on the Paris meeting later this week as negotiations proceed. I will be appearing each night this week on the Weather Channel’s Weather Underground program (#WUTV) to discuss the happenings in Paris. These segments will air at 6:40 pm EST on most if not all nights. A UN website includes more background on how this week’s negotiations will unfold. Many of the proceedings can be viewed on TV only within the convention center (and in some cases, not even there). If you’re interested in the step-by-step evolution of the agreement, complete with sometimes snarky context, check out this annotated Google Doc, which was updated frequently last week by a pair of college students from New Zealand who will be on site for the duration.

We’ll have our next post by Wednesday at the latest. WU blogger Steve Gregory has a new post covering the "warm wave" spreading over much of eastern North America over the next week, plus what may follow later in the month.

Bob Henson

El Niño Flood Climate Change Politics

Twisters Give Nation a Pass in 2015: Lowest Death Toll on Record?

By: Bob Henson , 6:25 PM GMT on December 04, 2015

Amid all the genuinely awful news making the rounds in recent days, here is one bright spot: the year 2015 may end up with the lowest number of U.S. tornado fatalities in at least 141 years. As of December 2, preliminary numbers from the NOAA Storm Prediction Center show only 10 tornado-related deaths nationwide. If this number holds through the end of the year, it will beat the 12 deaths reported in 1910 to become the lowest annual total on record. NOAA/SPC keeps tabs on tornado statistics, including fatalities, back to 1950. For earlier periods, veteran researcher Thomas Grazulis (author of the definitive volume “Significant Tornadoes 1680-1991”) has combed through newspapers and other archives to come up with the best existing data on tornado occurrence and fatalities as far back as 1875. If anything, the Grazulis numbers may be on the low side, which gives added confidence that the nation has indeed seen a remarkably safe year tornado-wise in 2015. The year is not done, though: 5 of the last 10 Decembers produced at least one tornado fatality, with the highest total of that period being 9 in December 2010.


Figure 1. Tornado deaths are far below the levels observed prior to the advent of the National Weather Service watch/warning system in the 1950s, although the catastrophic tornadoes of 2011 produced the biggest spike in fatalities in more than 80 years. Data provided courtesy Harold Brooks, NOAA National Severe Storms Laboratory; data sources are NWS (1950 – 2015) and Thomas Grazulis (1875 – 1949).


Figure 2. The EF4 tornado that plowed across northern Illinois just west of Chicago on April 9, 2015, photographed near Stillman Valley, Illinois. Image credit: wunderphotographer StormyPleasures (Charles Russell).


Figure 3. Wreckage lies along Illinois State Highway 64 near Rochelle, Illinois, on April 10, 2015, after an EF4 tornado struck the previous night. Image credit: Jon Durr/Getty Images)

Northwest flow cuts down on strength, frequency of tornadoes
Part of the story this year is sheer good luck. The strongest tornado of 2015 so far occurred on April 9: a violent EF4 twister that tracked over 30 miles of northern Illinois just west of Chicago. Just a small shift in that tornado’s track could have produced far more havoc. And the unseasonably late tornadic swarm of November 16 over the southern Great Plains produced three large EF3 tornadoes but comparatively little damage. Apart from these two outbreaks, the year’s crop of tornadoes was generally on the weak and short-lived side. A single outbreak can make an otherwise quiet year devastating, but in general, “a low number of tornadoes correlates to a low number of tornado deaths,” noted Greg Carbin, warning coordination meteorologist at NOAA/SPC, in an email.

After the horrific tornado season of 2011 (with 553 fatalities, the nation’s deadliest since 1925), the U.S. has seen four consecutive years with below-average activity, if we count 2015 in advance. For this quietude, we can thank the same predominant upper-level pattern that’s stoked four years of intense drought in California and shunted a large fraction of hurricanes away from the East Coast. “The stagnant large-scale pattern of generally northwest flow that has dominated central North America for the past few years has certainly played some role in suppressing conditions more supportive of tornado outbreaks,” Carbin said. “Whether this shift to more tranquil conditions is part of some longer-term oscillation, a result of climate change dynamics, or both, or just a random occurrence, is hard to say.”



Figure 4. The number of tornadoes in 2015 thus far is running about 25% below the 1954-2007 average for this time of year, when adjusted for multiple initial reports and for tornado “inflation” (the increased likehood in more recent years that a given tornado is documented). Image credit: NOAA Storm Prediction Center.

An uptick in tornado deaths over the last decade
Naturally, given the nature of his job, Carbin worries about the possibility that a quiet stretch could soften people’s resolve to keep themselves and their loved ones safe from tornadoes. The decade from 2005 to 2014 produced a total of 1092 tornado-related deaths. That’s roughly double the death rate that prevailed over the three prior decades (1975-84, 1985-94, and 1995-2004). Clearly, the numbers for the past decade are skewed by the huge death toll in 2011, but a total of six of the ten years in 2005-2014 produced at least 50 deaths. That wasn’t the case in any of the three previous decades.

“The annual death toll in the modern era is likely influenced more by the number of tornadoes than by our improved ability to predict them,” Carbin emphasized. “The conditions to support a widespread killer tornado outbreak can come together in a matter of 2-3 days. We need to maintain vigilance!”

Paris negotiations plow ahead
Diplomats from around the world continue to work on a 54-page draft of the agreement that organizers hope to finalize and adopt next week at the UN climate summit in Paris. One of the biggest points of difference right now is the maximum amount of global warming that emission cuts should allow for. The idea of keeping global temperature rise to no more than 2.0°C above preindustrial levels has been widely--but not universally accepted--for many years. There is nothing “magic” about 2.0°C, as significant impacts can be expected even at lower amounts of warming, and the effects would get progressively worse at higher amounts of warming. A group of nations now numbering more than 100 has been pushing for a maximum of 1.5°C rather than 2.0°C, a move that has gained momentum as well as resistance. We’ll have more on the Paris negotiations next week; in the meantime, I’ll be discussing the summit on Friday and through next week on the Weather Channel’s Weather Underground program (#WUTV). These segments will air at 6:40 pm EST on most if not all days.

Have a great weekend, everyone!

Bob Henson





Tornado

Holiday Shopping Guide for the Weather Enthusiast: Drones, PWSs, and Books

By: Jeff Masters , 4:42 PM GMT on December 03, 2015

If you really want to get a perfect angle for that awesome sunset you're planning to upload as a wunderphoto and get a coveted "Approver's Choice" award for, you need a drone. I recommend the DJI Phantom 3 Standard, which I purchased from Amazon for $999 back in July. The price has gone down to $669, which is a pretty amazing deal for a camera that will provide streaming video to your smart phone or tablet from up to 1/2 mile away, fly up to 400 feet high, and take 4000x3000 pixel still images or 2.7K video. The drone can fly up to 25 minutes with its lithium-ion battery. The Phantom 3 is tough, too--I've already crashed mine once by foolishly flying it too close to my house (the backwash from the propellers reflected off the walls and caused an unexpected deviation in the attitude of the drone, and I panicked and steered it into the gutter.) The drone fell ten feet to the ground, but was unharmed save for a few nicked propeller blades that I swapped out using the spares that came with the drone. Keep in mind that drones cannot be flown in National Parks, in downtown Washington D.C., near airports, or above 400 feet in altitude. If a drone is being used for commercial purposes, such as selling photos or videos, then the FAA requires explicit permission. You can learn more at the Know Before You Fly website, or the Pro Video Coalition's discussion of FAA drone rules as of September 2015.


Figure 1. Aerial view of Dunham Lake, Michigan in full fall splendor (an Approver's Choice wunderphoto!) taken this fall with my DJI Phantom 3 Standard drone.

Holiday books for the weather and climate science enthusiast
If you're bewildered by the complexity of the climate change/global warming issue, and want a comprehensive, easy-to-understand guide with great visuals that touches on all of the important issues, look no further than “Dire Predictions Understanding Climate Change: The Visual Guide to the Findings of the IPCC” by Penn State professors Michael Mann and Lee Kump. Dr. Mann is a leading climate scientist, and is also author of "The Hockey Stick and the Climate Wars", which I reviewed in 2012. Published in 2015 (second edition), "Dire Predictions" would make a great text for teaching a course on climate change at the high school or introductory college level. The book is separated into five sections: Climate Change Basics, Climate Change Projections, The Impacts of Climate Change, Vulnerability and Adaptation to Climate Change, and Solving Climate Change. Every page is filled with rich illustrations, graphs, and images that help get across the complexities of climate change; these visuals add considerable pizzazz so the topic is not boring. The book has a provocative section near the end on the morality of climate change and the urgency of climate change, and concludes with the words, "Climate change is the greatest challenge ever faced by human society. But it is a challenge that we must confront, for the alternative is a future that is unpalatable, and potentially unlivable. While it is clear that inaction will have dire consequences, it is likewise certain that a concerted effort on the part of humanity to act in its own best interests has great potential to result in success." The paperback version of “Dire Predictions” is $18.60 from Amazon.com. My only criticism of the book is that some of the historical data plots could have been updated to give data points closer to the publication year of 2015, but I give "Dire Predictions" five stars out of five. The book would be a nice companion to my recommendation from last year’s holiday gift guide, ”The Thinking Person’s Guide to Climate Change”, published in August 2014, by our very own Bob Henson.

Bob Henson has this recommendation: “A book called ’Secrets of The Greatest Snow on Earth’ might sound like a paid advertisement for the state of Utah. In fact, the state trademarked the slogan ‘Greatest Snow on Earth’ in 1975, but author Jim Steenburgh uses it liberally (with permission). Steenburgh’s book explains what makes the snow of the Beehive State, and in particular the Wasatch Range just east of Salt Lake City, so well suited for winter sports. But it also serves as a very appealing primer on snow meteorology as a whole. ‘The Greatest Snow on Earth’ is a colorful paperback, filled with photos as well as beautifully rendered maps and scientific explanations. Steenburgh, a meteorology professor at the University of Utah, is a snow lover himself, and the writing is sprinkled with skier/boarder lingo as well as handy explanations for those of us unfamiliar with dust-on-crust, blower pow, or right-side-up snowfall. The book is an easy, informative, and engaging read while also staying scientifically rock-solid. Steenburgh explores big-snow regimes around the world, reviews avalanche safety and prevention, and examines how climate change could affect snowfall in Utah. This book is an ideal gift for someone who’s passionate about alpine snow sports and/or curious about the amazing weather that makes them possible. ‘Secrets of the Greatest Snow on Earth’ is available for $15.66 in paperback or $10.99 as a Kindle ebook from Amazon. I give it a solid five stars out of five.”



A Personal Weather Station: yes!
Every serious weather enthusiast deserves a Personal Weather Station (PWS) in their backyard! Not only can you enjoy seeing what the weather is in your backyard, you can share the data with everyone else on the Internet by uploading to the wunderground Personal Weather Station network, which boasts data from over 140,000 stations. You don’t need to have a computer on all the time to collect the data and send it to the Internet—a WeatherBridge device will keep the data flowing to the Internet even when your computer is turned off. A full list of wunderground-compatible PWS models, software, and add-ons like the Ambient WeatherBridge is available from our Personal Weather Station buying guide page. A few recommendations I have:

Weather station for a smart phone: Netatmo
The Netatmo Weather Monitor ($129) contains a unique set of sensors to monitor your living environment and wirelessly transmits all your data to your Smartphone. The Netatmo App displays your station’s indoor and outdoor measurements into clear and comprehensive dashboards, graphs and notifications. 

A low-end PWS choice: Davis Vantage Vue
The Davis Vantage Vue + WeatherBridge Package is $625 from ambientweather.com. Combine the convenience of WeatherBridge with Davis Instruments' Vantage Vue™ station which is fully featured, highly accurate and affordably priced.

A high-end PWS choice: Rainwise
I have had a Davis Vantage Pro2 in my backyard for the past seven years, and have been very happy with it, but I also recommend the RainWise Direct to Weather Underground Package, $999 from rainwise.com. The RainWise RapidFire™ enabled weather station doesn't need a PC to upload to us, and with an ultra-fast refresh rate of every 3-5 seconds, new data is updated instantly.

A webcam choice: Ubiquiti Networks AirCam
The AirCam Indoor/Outdoor IP Camera from Ubiquiti Networks ($130) combines advanced industrial design and powerful performance.



Weather Underground T-shirts and hoodies
The Weather Underground store has an assortment of T-shirts and hoodies available for 10% off through January 1 when you use this promotion code: WUFANSAVE10.

Jeff Masters (with Bob Henson contributing to the book reviews)

Book and Movie Reviews

Top Ten 2015 Atlantic Hurricane Season Events; Paris Climate Talks Ramp Up

By: Jeff Masters and Bob Henson , 3:50 PM GMT on December 01, 2015

The 2015 Atlantic hurricane season is officially over, and it will go into the books as the most memorable hurricane season to occur during a strong El Niño event. Strong El Niño events typically reduce Atlantic hurricane activity by increasing wind shear over the tropical Atlantic, and this year's El Niño conditions did indeed create unusually high levels of wind shear over the Caribbean, making it difficult for tropical systems to organize and strengthen in those waters. According to Colorado State's Dr. Phil Klotzbach, the 200-850-mb vertical wind shear in the Caribbean (10-20°N, 90-60°W) averaged from June through October was the highest since at least 1979 (28.5 knots.) However, this high wind shear did not extend as far east as usual, allowing several tropical storms to form near the coast of Africa over waters that were near-record warm. Near record-warm to record-warm ocean temperatures were also over more northern reaches of the Atlantic, and helped spur the formation of Hurricane Joaquin and Hurricane Kate. As a result, the 2015 season was able to tally numbers that were not that far below average--11 named storms, 4 hurricanes, and 2 intense Category 3 or stronger hurricanes. The 1981-2010 average numbers were 11.5 named storms, 6.1 hurricanes, and 2.6 major hurricanes. Accumulated Cyclone Energy (ACE) is a measure of the total destructive power of a hurricane season, based on the number of days strong winds are observed. ACE for an individual storm is computed by squaring the maximum sustained winds of the storm at each 6-hourly advisory, and summing up over the entire lifetime of the storm. The ACE for the 2015 Atlantic hurricane season was about 60% of average, reflecting the relative lack of hurricanes. Hurricane Joaquin accounted for 46% of the season's ACE.


Figure 1. Preliminary paths of all the named Atlantic storms of 2015, except for Hurricane Kate, which has not yet been added. Image credit: NOAA/NHC.


Figure 2. Vertical wind shear across the Caribbean averaged from June through October for each of the years 1979 through 2015. Wind shear in 2015 was the strongest on record. Image credit: Phil Klotzbach's and Bill Gray's November 30 season summary (CSU.)

Top ten notable events of the 2015 Atlantic hurricane season
Here's my top-ten list of events of the 2015 Atlantic hurricane season--some of them taken from Colorado State's Dr. Phil Klotzbach's November 30 summary:

1) Hurricane Joaquin was the strongest Atlantic hurricane since 2007, topping out just below Category 5 strength on October 3 with 155 mph winds. Joaquin was the second deadliest and second most damaging Atlantic named storm of 2015, causing $100 million in damage in the Central Bahamas, where it lingered for several days. Joaquin's death toll was 35, with 33 of these deaths occurring from the sinking of the ill-fated cargo ship El Faro. Although Joaquin tracked far to the east of the United States, a non-tropical low over the Southeast tapped into the hurricane's moisture, causing record-shattering rains and flooding across North and South Carolina. Several areas of South Carolina saw accumulations exceeding the threshold for a 1-in-1,000-year event. The subsequent floods inundated large areas of the state, killing 19 people and causing over $2 billion in damage.


Figure 3. Hurricane Joaquin as seen by the GOES-East satellite at 7:45 am EDT October 1, 2015. At the time, Joaquin was an intensifying Category 2 storm with 110 mph winds. The last position of the cargo ship El Faro, in the northwestern eyewall of Joaquin, is shown. Image credit: United States Navy and NOAA.

2) Tropical Storm Erika was the deadliest and most expensive Atlantic storm of 2015. Erika unleashed a catastrophic deluge on August 27 that brought extreme flooding to the Caribbean island of Dominica (population 72,000), causing its most expensive disaster in history. The storm did $612.7 million in damage in East Caribbean dollars to roads and bridges, $39.5 million in damage to the airport, and an additional $12 million in clean up costs (thanks go to David C. Adams of Thomson Reuters for this info.) Erika's total preliminary price tag of $275 million U.S. dollars is not far from Dominica's annual GDP of $500 million. The storm will likely set the island back 20 years in development, Prime Minister Skerrit said. According to EM-DAT, the international disaster database, Dominica's previous most expensive disaster was the $175 million in damage from Hurricane Marilyn of 1995. Erika's death toll of 36 makes it the 3rd deadliest disaster in Dominica's history, behind the 40 killed in 1979's Hurricane David and the 2,000 people killed in Dominica by The Dominican Republic Hurricane of 1930.


Video 1. Floodwaters rage through a street on Dominica island in the Caribbean on Thursday, August 27, 2015, after Tropical Storm Erika dumped 12+" of rain on the island.

3) Hurricane Fred. For the first time since 1892, a full-fledged hurricane pounded the Cape Verde islands, when Hurricane Fred intensified to a Category 1 storm with 85 mph winds as it passed through the islands on August 31. Fortunately, Fred missed making a direct hit on any of the islands, and damage was less than $2 million. However, Fred brought violent seas to the West African coast, damaging or destroying numerous fishing villages in Senegal. Between the coasts of West Africa and Cape Verde, maritime incidents related to Fred resulted in 9 deaths (Wikipedia.) Fred became a hurricane at 22.5°W longitude, the easternmost formation location in the tropical Atlantic for any hurricane in the historical record. The previous record was held by Hurricane Three of 1900, which became a hurricane at 23°W, south of the Cape Verde islands.


Figure 4. MODIS image of Hurricane Fred from NASA's Terra satellite taken at approximately 11:15 am EDT Monday August 31, 2015. At the time, Fred was at peak strength with top sustained winds of 85 mph. Image credit: NASA.

4) No major hurricanes made US landfall in 2015. The last major hurricane to make US landfall was Wilma (2005), so the US has now gone ten years without a major hurricane landfall. In records going back to 1851, the US has never had a ten-year period without a major hurricane landfall, eclipsing the previous record of eight years set from 1861-1868.

5) Florida went without a hurricane impact for the 10th consecutive year. This is the longest consecutive year period on record that Florida has not had a landfall since records began in 1851. The longest previous record was five years, set from 1980- 1984.

6) Ocean temperatures in the Caribbean were the warmest on record in October, yet no storms formed in the Caribbean and only one (Erika) tracked into the Caribbean. This is because June-October-averaged 200-850-mb vertical wind shear in the Caribbean (10-20°N, 90-60°W) was 28.5 knots--the strongest on record (since 1979).

7) Hurricane Danny. Despite strong El Niño conditions developing in the Eastern Pacific, a major hurricane managed to form in the Main Development Region (MDR) of the tropical Atlantic, between the coast of Africa and the Caribbean. Hurricane Danny only lasted six hours as a major hurricane, and high wind shear and dry air destroyed the storm just as it arrived in the Lesser Antilles Islands.


Figure 5. Hurricane Danny as viewed from the International Space Station and tweeted on Thursday morning, August 20, by astronaut Scott Kelly. At the time, Danny was an intensifying Category 1 hurricane with 80 mph winds. Image credit: NASA.

8) Only four hurricanes formed in 2015. This brings the combined 2013-2015 total to 12 hurricanes. This is the lowest three-year total since 1992-1994 (11 hurricanes).

9) Two major hurricanes formed in 2015. This brings the combined 2013- 2015 total to 4. No three-year average has been lower since 1992-1994 (2 major hurricanes).

10) Hurricane Kate became the Atlantic’s most intense tropical cyclone on record for November during the five years since 1950 with strong El Niño conditions present in October-December: 2015, 1997, 1982, 1972, and 1965. Only one other named system was observed during those Novembers: 1972’s Subtropical Storm Delta.


Video 1. WU member Brian Osborne created this impressive 18-minute long video of over 10,000 GOES-East images showing the evolution of the 2015 Atlantic hurricane season. Particularly interesting is the portion about 12 minutes in, when we see Hurricane Joaquin form, plow into the Central Bahamas, then turn a firehose of moisture into South Carolina that gets wrapped around an upper-level low pressure system.

Day 1 of the Paris climate summit: Leaders weigh in
More than a week of tough negotiations lies ahead at the UN Climate Conference (COP21), but Monday--the opening day--was a time for reflection and expression of common purpose. More than 150 heads of state were on hand, and dozens of them gave speeches, acknowledging the gravity of human-produced climate change and the daunting task of turning it around. These themes were delivered in many flavors. Canada’s new prime minister, Justin Trudeau, stayed upbeat while alluding to his nation’s having bowed out of the Kyoto Protocol: “Canada is back, my friends. Canada is back, and here to help.” France’s president, Francois Hollande, was understandably grave: “...never have the stakes been so high because this is about the future of the planet, the future of life. And yet two weeks ago, here in Paris itself, a group of fanatics was sowing the seeds of death in the streets.” British Prime Minister David Cameron brought the issue to a familial scale--“Let’s just imagine for a moment what we would have to say to our grandchildren if we failed”--while the prime minister of Slovenia, Miro Cerar, harked back to a quote by the late US president Dwight Eisenhower: “As we peer into society’s future, we--you and I, and our government--must avoid the impulse to live only for today, plundering for our own ease and convenience the precious resources of tomorrow.”

As in past summits, some of the most poignant remarks came from the leaders of island nations threatened soonest by rising sea levels and storm surge. Marshall Islands president Christopher Loeak put it this way: “The climate we have known over many centuries has in a matter of three short decades, changed dramatically, before our very eyes. We are already limping from climate disaster to climate disaster and we know that there is worse to come. For us, COP21 must be a turning point in history. And one that gives us hope.” Many of the smaller island states are maintaining their longtime push to keep global warming at no more than 1.5°C above preindustrial levels--perhaps a quixotic goal at this point, given the record global warmth of 2014 and 2015 and the possibility that 2016 will be warmer still. On the brighter side, India announced on Monday that it will spearhead a new global alliance of 120 nations aimed at vastly expanding the reach of solar power to developing towns and cities across the tropics. The new alliance will serve as a framework through which agencies and industry can take advantage of economies of scale in bringing solar power to underserved areas. Although restricting fossil fuels is sometimes viewed as a roadblock to economic development for the world’s poorest residents, it’s quite possible that initiatives like these could be just the opposite--a way to leapfrog over current logistical barriers and move directly toward clean, accessible power.

See our Monday post for more on the Paris summit, including links to frequently updated news sources. Wunderground's climate change blogger, Dr. Ricky Rood, has an interesting new Tuesday afternoon post on the Paris climate summit called All Fracked Up.

Our next post will be Wednesday or Thursday.

Jeff Masters (tropical], Bob Henson [Paris summit]


Figure 6. The Eiffel Tower was lit up in green on November 30 during the first day of the United Nations climate conference in Paris. Image credit: Stephane de Sakutin/AFP/Getty Images.

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

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