Atmospheric Scientist here at Weather Underground, with serious nerd love for tropical cyclones and climate change. Twitter: @WunderAngela
By: angelafritz, 2:15 PM GMT on December 31, 2012
Another extreme year in weather has passed, the most extreme year in record-keeping, according to the National Climatic Data Center. The U.S. saw 11 billion-dollar weather disasters in 2012, including drought, wildfire, 2 hurricanes, and severe weather events. Though climate extremes are increasing across the globe—in Africa, Europe, Asia, Australia—no country topped the U.S. in extremes in 2012, and an increase in extreme weather is an impact expected in a warming world. There are more direct changes being seen, too, in the Arctic, and Greenland, and in our jet stream. Below are what I consider the top climate events of 2012.
Superstorm Sandy was truly astounding in its size and power. At its peak size, twenty hours before landfall, Hurricane Sandy had tropical storm-force winds that covered an area nearly one-fifth the area of the contiguous United States. Most incredibly, ten hours before landfall, the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terrajoules--the highest value for any Atlantic hurricane since at least 1969, and equivalent to five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been larger. Over 130 fatalities were reported and over 8.5 million customers lost power--the second largest weather-related power outage in U.S. history, behind the 10 million that lost power during the Blizzard of 1993. Damage from Sandy is estimated at $62 billion.
Hurricane Sandy approaching the East Coast on October 28, 2012.
While Sandy was not an extreme "black swan" hurricane, its climate connections are hard to ignore. Sea surface temperature off the East Coast was abnormally warm this summer, which gave Sandy the fuel it needed to maintain its strong winds as it traveled north out of the Caribbean and to the Northeast. Sea level continues to rise, giving storms like Sandy a higher starting point to flood areas (like New York City) that have seen storm surges only rarely in the past. (More on sea level rise from Climate Central.) Maybe most crucially, the atmospheric pattern that we saw leading up to and during Superstorm Sandy could have been the result of diminishing Arctic sea ice, according to a study published this year by Jennifer A. Francis (Rutgers University) and Stephen J. Vavrus (University of Wisconsin-Madison), which found that sea ice loss is linked to increased atmospheric wave amplitude. In other words, less Arctic sea ice means more extreme and abnormal weather, especially drought, floods, cold spells, and heat waves. In relation to Sandy, we saw an extreme atmospheric "blocking" pattern as Sandy approached the U.S., which allowed the storm to jack-knife to the west into the coast, instead of heading east out to sea, which is more typical of North Atlantic hurricanes.
In the wake of Superstorm Sandy, New Yorkers were awakened to the issue of climate change and its potential (and current) threat to lives and property. According to a poll released in early December, the majority of New Yorkers think that the hurricane/superstorm was evidence of climate change, rather than just an isolated weather event. New York City Mayor Michael Bloomberg endorsed President Obama in the 2012 presidential election post-Sandy, citing climate change. “Our climate is changing,” Mayor Bloomberg wrote. “And while the increase in extreme weather we have experienced in New York City and around the world may or may not be the result of it, the risk that it may be—given the devastation it is wreaking—should be enough to compel all elected leaders to take immediate action.” And of course, Businessweek ran a cover story after the storm that we can hardly forget.
Hottest Year on Record in Contiguous U.S.
The first half of 2012 was so warm that by early August, the U.S. had already exceeded the number of record-high temperatures set or tied during all of 2011. 2012 was the hottest year on record in the lower 48 of the United States. In line with the global warming trend spurred by steadily rising carbon emissions, seven of the top 10 warmest years in the 48 states have occurred in the past 15 years. Like so much recent record-breaking weather, 2012 isn’t just going to top the previous record, 2012 is looking to smash it, by more than 1°F. The year-to-date period of January to November was by far the warmest such period on record for the contiguous U.S.—a remarkable 1.0°F above the previous record. During the 11-month period, 18 states were record warm and an additional 24 states were top ten warm. In mid-December, Climate Central projected that 2012 average temperature for the continental U.S. at 55.34°F compared to the previous record set in 1998 of 54.32°F. For perspective, 1°F is one-quarter of the difference between the coldest and warmest years ever recorded in the U.S.
The Great Drought of 2012
The Great U.S. Drought of 2012 is likely biggest weather story of 2012, since its full impacts have not yet been realized. The area of the contiguous U.S. in moderate or greater drought peaked at 61.8% in July—the largest such area since the Dust Bowl drought of December 1939. The heat and dryness resulted in record or near-record evaporation rates, causing major impact on corn, soybean and wheat belts in addition to livestock production. Crop damages alone from the great drought are estimated at $35 billion. As the total scope of losses is realized across all lines of business in coming months, this number will climb significantly. Drought upstream of the Lower Mississippi River caused record and near-record low stream flows along the river in Mississippi and Louisiana, resulting in limited river transportation and commerce. Now, with winter ice forming at the northern end of the river, traffic is likely to be disrupted again soon. Dredging has been ongoing since July.
Figure 3. Corn in Colby, Kansas withers in the Great Drought of 2012 on May 27. Image credit: Wunderphotographer treeman.
333 Months of Warmer Than Average Temperature (and Counting)
November 2012 was Earth's 333rd consecutive month above average, and counting. Writes Jeff Masters, "the last time Earth had a below-average November global temperature was in 1976, and the last below-average month of any kind was February 1985--during the Reagan administration, when the cost of a first-class stamp was 20 cents." Maybe more alarming, as Grist writes, If you’re 27 or younger, you’ve never experienced a colder-than-average month. A preponderance of scientific evidence shows this trend is due in large part to man-made emissions of greenhouse gases, such as carbon dioxide, and is likely to continue.
Departure of temperature from average for November 2012, the 5th warmest November for the globe since record keeping began in 1880.
Record Low Arctic Sea Ice
The Arctic saw record low sea ice extent in September 2012. The ice extent bottomed out at 3.41 million square kilometers, breaking the previous all-time low set in 2007 by 18%, despite more favorable weather for the Arctic ice in 2012. 49% of the ice cap was gone this year. For the fifth consecutive year, and for the fifth time in history, ice-free navigation was possible in the Arctic along the coasts of Canada and Russia. "We are now in uncharted territory," said NSIDC Director Mark Serreze. "While we've long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur. While lots of people talk about opening of the Northwest Passage through the Canadian Arctic islands and the Northern Sea Route along the Russian coast, twenty years from now from now in August you might be able to take a ship right across the Arctic Ocean."
A powerful storm wreaked havoc on the Arctic sea ice cover in August 2012. This visualization shows the strength and direction of the winds and their impact on the ice: the red vectors represent the fastest winds, while blue vectors stand for slower winds. According to NSIDC, the storm sped up the loss of the thin ice that appears to have been already on the verge of melting completely.Video credit: NASA.
Not only was the Arctic ice-free for navigation, but it was also ice-free for oil drilling. Shell oil has its sights set on the Arctic sea floor off the coast of northern Alaska. However, the oil giant has been thwarted a number of times this year by weather and technology, and in particular, the failure of the testing of their containment dome, which is designed to capture and seal off oil from the surrounding environment in the event of a spill. The mechanics on the dome failed as it was being lowered into the water for tests.
Huge Greenland Ice Sheet Melt
97% of Greenland underwent surface melting on July 12, 2012—an event completely unprecedented in 30 years of satellite measurements. The melt was confirmed in a press release from NASA, in which researcher Son Nghiem said, "This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?" Melt maps derived from three different satellites showed that on July 8, about 40 percent of the ice sheet's surface had melted, as a strong ridge of high pressure set up over Greenland. By July 12, the melting had expanded to cover 97% of Greenland. Temperatures at at the top of the Greenland Ice Sheet, 10,551 feet (3216 meters) above sea level, and 415 miles (670 km) north of the Arctic Circle, had risen above the freezing mark four times in the 12-year span 2000 - 2011. But in mid-July 2012, temperatures eclipsed the freezing mark on five days, including four days in a row from July 11 - 14. Interestingly, ice core records show that in 1889, a similar pronounced melt event occurred at the top of the Greenland Ice Sheet, and such events occur naturally about every 150 years. "But if we continue to observe melting events like this in upcoming years, it will be worrisome," said Lora Koenig, a NASA/Goddard glaciologist and a member of the research team analyzing the satellite data.
Melt water from the record July temperatures in Greenland fed the raging Watson River, which smashed two bridges connecting the north and south of Kangerlussuaq (Sønder Strømfjord), a small settlement in southwestern Greenland. The flow rate of 3.5 million liters/sec was almost double the previous record flow rate.
The U.S. wildfire season in 2012 was the 3rd worst in recorded history. More than 9.1 million acres burned across the United States in 2012. Since the National Interagency Fire Center began keeping records in 1960, only two years have seen more area burned--2006, when 9.9 million acres burned, and 2007, when 9.3 million acres burned. These fires included the most destructive and 2nd largest wildfire in Colorado history, the Waldo Canyon Fire, which burned over 18,000 acres near Colorado Springs and destroyed 346 homes. The High Park Fire of 2012, which burned nearly 90,000 acres, had been Colorado's largest fire, until that record was broken again by the Waldo Canyon Fire just a few days later. The Whitewater-Baldy Complex fire was the largest in New Mexico state history, burning almost 300,000 acres, and the Little Bear Fire, which burned over 44,000 acres, was the state's most destructive fire. Oregon also saw it's largest wildfire in 150 years in the Long Draw Fire, which burned approximately 720,000 acres. U.S. wildfires were a billion-dollar weather disaster for the U.S. in 2012, according to the National Climatic Data Center.
Fire from the Waldo Canyon wildfire burns as it moved into subdivisions and destroyed homes in Colorado Springs, Colo., on Tuesday, June 26, 2012. (AP Photo/Gaylon Wampler)
A large increase in wildfires over much of the globe is expected as we move through this century. Researchers have found that 38% of the planet will see increases in fire activity over the next 30 years. This figure increases to 62% by the end of the century. However, in many regions where precipitation is expected to increase—particularly in the tropics—there should be decreased fire activity. The scientists predicted that 8% of Earth will see decreases in fire probability over the next 30 years, and 20% will see decreases by the end of the century. The models do not agree on how fire danger will change for a large portion of the planet--54% for the period 2010 - 2039, and 18% for the period 2070 - 2099.
The Non-Winter of 2011-2012
The contiguous U.S. saw its 3rd lowest snow cover on record during both winter and spring, and the winter of 2011 - 2012 was the 4th warmest and 24th driest winter in U.S. history, going back to 1895. A primary cause of this warm and snowless winter was the most extreme configuration of the jet stream ever recorded, as measured by the North Atlantic Oscillation (NAO). The NAO index was +2.52 in December 2011, which was the most extreme difference in pressure between Iceland and the Azores ever observed in December (records of the NAO go back to 1865.) The positive NAO conditions caused the Icelandic Low to draw a strong south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward over the U.S. This jet pattern is consistent with what research suggests could be the result of shrinking Arctic sea ice. This study found that less Arctic sea ice means more extreme and abnormal weather, especially drought, floods, cold spells, and heat waves.
Europe's Extreme Cold Snap
Europe experienced a historic deadly cold wave in January-February of 2012 that bright snow, sleet, and freezing rain to much of the continent. The harsh winter conditions killed over 800 people. The lowest temperature reached during the cold snap was -39.2°C (-38.2°F). A rare snow storm hit North Africa, which brought 2 - 3 inches of snow to Tripoli, Libya. It was the first snow in Tripoli since at least 2005, and may be the heaviest snow the Libyan capital has seen since February 6, 1956. According to weather records researcher Maximiliano Herrera, the cold snap was the most severe for Europe since February 1991.
Wunderphoto taken in Croatia on February 5, 2012 from antoniomise, who wrote, "snow in Dalmatia, frozen streets....sounds impossible but it happened! Snow is still present. In this part of world this is phenomena."
Similar to Sandy, Europe can blame the jet stream for their extreme weather. During this cold wave, the jet had a highly convoluted shape, with unusually large excursions to the north and south. When the jet bulges southwards, it allows cold air to spill in behind it, and that is what happened to Europe at the end of January and the beginning of February. The jet often gets "stuck" in one of these highly convoluted shapes, allowing a persistent period of extreme weather to occur. Again, this jet pattern is consistent with what research suggests could be the result of shrinking Arctic sea ice. This study found that less Arctic sea ice means more extreme and abnormal weather, especially drought, floods, cold spells, and heat waves.
Dr. Jeff Masters, Shaun Tanner, and Climate Central contributed to this post.
By: angelafritz, 5:00 AM GMT on December 26, 2012
Severe storms are expected to continue in the Southeast U.S. tonight, and you can read a recap of today's storms in Shaun Tanner's blog. Our preliminary tornado count is 21 (up from 19 earlier), which could be a new Christmas Day record (see below for more Christmas Day tornado statistics). The Storm Prediction Center has extended the "moderate risk" of severe weather into Wednesday, though don't be fooled by the term "moderate" -- this is a very dangerous storm with a history of producing large, incredibly destructive tornadoes. The highest risk for tornadoes on Wednesday exists in the central to eastern Carolinas. Like Tuesday, the tornado threat will begin in the morning, and strong, long-track supercell thunderstorms and tornadoes will be possible, especially entering the afternoon and evening hours. Widespread, damaging wind gusts are also likely. Thunderstorms with large hail and damaging wind will spread across Georgia and Florida throughout the day as the line moves eastward with the storm.
Stay up to date with Wundermap: Check your county's advisories.
Current Northeast U.S. weather advisories.
Current Southeast U.S. weather advisories.
Stay up to date with Wundermap: Check your county's advisories.
On Tuesday night, winter weather advisories related to this storm extended from Texas and Oklahoma to Maine, covering 21 states. Driving in northern Texas was a nightmare as roads iced over. I-35 and I-30 around Dallas were particularly treacherous. Thundersnow was reported near the North Little Rock Airport in Arkansas around 9pm CST Tuesday evening, which confirms that this storm is powerful with strong uplift. Snow, blizzard conditions, and wintry mix will be easing up in Oklahoma, Texas, Missouri, and Arkansas by mid-morning on Wednesday. Blizzard conditions are expected to either continue or begin on Wednesday from southern Illinois and western Kentucky up through northeast Ohio.
Heavy snow is falling Tuesday evening in central Arkansas north of Little Rock. Blizzard conditions will remain possible through Wednesday morning in the northeast portion of the state. Little Rock, Arkansas saw it's snowiest day since January 6, 1988 on Tuesday. 12" of snow was reported in Vandervoort, AR, and 7.5 inches fell in Pine Ridge, AR. Both of these observations were taken around 8pm CST on Tuesday.
The heavy snow, which began Tuesday night, will be confined to the southeast part of Missouri, though a dusting to a couple of inches could accumulate in Springfield and St. Louis. Wind gusts could reach 40 mph, and a blizzard warning is in effect for far southeast Missouri until 12pm CST on Wednesday, meaning visibility will likely be low and travel will be difficult. 6-12 inches of snow is possible in southeast Missouri.
Very heavy rain is falling in Tennessee on Tuesday evening, and a winter weather advisory is in effect for far western counties, including the city of Nashville, until 4pm CST on Wednesday. 1-2 inches of snow accumulation is expected there after rain changes to snow late in the morning and into the afternoon.
Snow showers and a wintry mix have begun in southern Illinois on Tuesday night. This will turn to all snow overnight. The heaviest snow will fall in southern Illinois, where 6-12 inches of snow is expected to fall. In the northern portion of the warned areas (Olney, Effingham, Mattoon, Paris) 4-9 inches will be more common. Wind gusts could reach 40 mph, and a blizzard warning is in effect for southeast Illinois until 12pm CST on Wednesday, which means visibility will be low and travel will be difficult.
A wintry mix will turn into snow overnight and snow will being to taper off late Wednesday morning. Wind gusts could reach 45 mph, and a blizzard warning is in effect until 12pm CST on Wednesday in southern Indiana, and until 7pm EST in central Indiana. Visibility will be low and travel will be difficult.
4-8 inches is expected in far southern Indiana
10-14 inches of snow is expected in south-central Indiana
8-12 inches of snow is expected in east-central Indiana
A wintry mix will turn into snow overnight and snow will being to taper off late Wednesday morning. Heavy snow will be confined to the far western part of the state. 8-12 inches is possible. Winds could gust up to 45 mph and a blizzard warning is in effect, which means visibility will be low and travel will be difficult.
In southern Michigan, accumulations of 3-5 inches will be common. Winds could gust up to 25 mph.
Snow will begin in southeast Ohio after midnight on Tuesday. The southeast part of the state should expect about 6-10 inches of snow, though Cincinnati and cities east of Cincinnati will see much less. 6-10 inches of snow will fall in the eastern part of the state, including Dayton, Columbus, and Toledo. 8-12 inches is possible east of I-71. Winds could gust up to 45 mph, and a blizzard warning is in effect along a line from southeast to northeast Ohio until 7am EST on Thursday. Freezing rain and sleet is possible in far southeast Ohio, with ice accumulation to about a tenth of an inch. Snow will begin to taper off from west to east on Wednesday night.
Snow will begin in the northwest part of the state on Wednesday morning and early afternoon. In the northwest, 8-12 inches of snow is possible. Erie County along the Lake Erie coast is under a blizzard warning until 7am EST Thursday. Less snow will fall in eastern Pennsylvania, though snow will change to a wintry mix and freezing rain in the south and southeast parts of the state on Wednesday evening. Philadelphia and the surrounding area will remain in rain.
Freezing rain and sleet will be the biggest hazard in West Virginia. Freezing rain will begin on Wednesday morning and last until Wednesday night. Up to a quarter of an inch of ice is expected to accumulate, which will likely bring down branches and power lines, and make driving near impossible. It's recommended that driving be avoided altogether in areas under the freezing rain advisories and ice storm warnings. Winds will also be gusting to 45 mph.
Ice and snow will extend into western Virginia beginning Wednesday morning. 2-5 inches of snow and sleet will accumulate, with the highest amounts falling in the ridges. One to two tenths of an inch of ice will also accumulate west of the Blue Ridge by early Thursday morning. Freezing rain will likely bring down branches and power lines, and driving will be extremely hazardous. Winds will gust up to 35 mph. Precipitation will remain mostly rain (though some wintry mix is possible) east of Charlottesville, Lynchburg, and Roanoke.
In western Maryland, 4-8 inches of snow will accumulate. The snow will likely be mixed with freezing rain and sleet late Wednesday morning into the afternoon. A tenth of an inch of ice could accumulate. Winds will gust up to 40 mph. Snow and ice will extend as far east as Washington D.C., which will see snow changing to wintry mix by Wednesday afternoon.
Snow will begin in New York late Wednesday afternoon. Accumulations if 8-16 inches will be common. The heaviest snow will fall overnight on Wednesday. Snow will turn to wintry mix and freezing rain Wednesday night for the southeastern part of the state. Winds will gust up to 30 mph. New York City and the surrounding area will remain mostly rain, though a wintry mix of sleet and freezing rain will be possible.
Snow, sleet, and possibly some freezing rain will begin in Connecticut on Wednesday evening. 4-8 inches of snow could fall away from the coast, and a trace of ice could also accumulate, making roads very slick. Winds could gust up to 45 mph.
Snow, sleet, and possibly some freezing rain will begin in Massachusetts on Wednesday evening. 4-8 inches of snow could fall away from the coast, and a trace of ice could also accumulate, making roads very slick. Boston will remain mostly rain, though some wintry mix is possible, especially in the western suburbs. Winds could gust up to 45 mph.
Snow will begin in Vermont on Wednesday evening and taper off by Friday morning. 8-14 inches of snow is expected in southern Vermont, while northern Vermont should expect 10-15 inches. Winds could gust up to 30 mph.
Snow will begin in New Hampshire on Wednesday evening and last through Thursday night. Around a foot of snow will fall in New Hampshire, with higher amounts in the mountains and lower amounts in the valleys. Winds could gust up to 40 mph.
Snow will begin in Maine on Wednesday evening and last through Thursday night. Around a foot of snow will accumulate, with higher amounts in the mountains and lower amounts in the valleys. In northern Maine, 10-16 inches of snow is possible. Winds could gust up to 40 mph.
Stay up to date with Wundermap: Check your county's advisories.
Notable Tornadoes of Christmas Past
From the National Weather Service in Washington D.C.
--Dec. 24-25, 1964: 14 tornadoes (three of them F3), Alabama, Florida, Georgia, North Carolina, South Carolina, Tennessee, West Virginia. Two deaths in Georgia; about 30 people injured.
--Dec. 25, 1969: 12 tornadoes (two F3) in Florida, Georgia, Louisiana One death in Louisiana, 17 injuries.
--Dec. 25-26, 1973: 7 tornadoes, two of them F2, in Alabama, Florida, Georgia. Two injuries.
--Dec. 24, 1975: 3 tornadoes (one F3) in Texas and Florida. No injuries or deaths.
--Dec. 24-25, 1977: 3 tornadoes (1 F3) in Mississippi and Florida. Seven injuries.
--Dec. 24-26, 1982: 29 tornadoes (one F4, two F3), in Oklahoma, Missouri, Arkansas, Tennessee, Mississippi. Three deaths in Arkansas and Missouri; 32 injuries.
--Dec. 24, 1988; 1 tornado (F4) in Tennessee. One death; seven injuries.
--Dec. 24, 1997: 3 tornadoes (one F2) in Alabama. Five injured.
--Dec. 25, 2006: 6 tornadoes (four F2) in Georgia and Florida. 14 injured.
--Dec. 24, 2009: 22 tornadoes (three F2) in Texas, Louisiana and Mississippi. Four injured.
--Alabama, Georgia, Louisiana, Mississippi, and Florida are the most likely states to have tornado events around this time of year.
--The last time a number of tornadoes impacted the Gulf Coast area around Christmas Day was in 2009, when 22 tornadoes occurred during the morning of December 24th.
--In over 60 years there have been two EF4-rated tornadoes on Christmas Eve, one in 1982 in Arkansas, the other in 1988 in Tennessee.
--The last killer tornado around Christmas was a Christmas Eve F4 in Tennessee in 1988, killing one person and injuring 7.
P.S. I'm here in Cleveland, Ohio for the holiday, so I promise to head out into the blizzard on Wednesday to make some observations.
Updated: 6:07 PM GMT on December 26, 2012