Warmest December in U.S. history ends stormy, mostly red-hot year


Bob Hansen, Yale Climate Connection. Originally Posted on Yale Climate Connection.

In addition to a catastrophic cold snap, warm-season threats from tornadoes to wildfires — regardless of the calendar — will cause most of the contiguous U.S. weather damage in 2021.The year generated $20 billion in disasters, the second-highest number according to NOAA Inflation Adjusted Data Dating back to 1980. The total cost of disasters worth $1 billion in 2021 is $145 billion, the third-highest on record since 1980.

In its preliminary annual summary of the U.S. climate, released Jan. 10, NOAA found 2021 to be the fourth warmest year on record for 48 contiguous states.Most of the warmth is concentrated in the second half of the year, the national Warmest July-December period on record.

In data going back to 1895, the only U.S. years that were warmer than 2021 were 2012, 2016 and 2017. Temperatures in the lower 48 states have been above the 1901-2000 average every year since 1996, with the seven warmest years on record all occurring on 21stone century.

Adjacent US is warming now about 2.0°F (1.1°C) Since 1895, this is similar global average. This is a notable trend given that the United States lagged much of the globe in long-term warming in the late 20th century.

According to preliminary data from NOAA compile Independent meteorologist Guy Walton said the U.S. daily record maximum (34,569) in 2021 is nearly three times the daily record minimum (12,644). That puts 2021 at a ratio of more than 2 to 1 for all-time highs to all-time lows for the second year in a row. A 2009 paper by Walton and colleagues expected The typical ratio could be 20 to 1 by mid-century and 50 to 1 by the end of the century.

In 2021, each of the 48 consecutive states saw warmer-than-average temperatures, with 35 of those states in the top 10 for their warmest years. Yearly warmth in the Southern Plains and Southeast has only waned slightly, largely as a result of the brutal cold wave that swept across much of the central U.S. in mid-February.

A total of 106 stations hit or matched record lows in February. The intensity and duration of the severe cold was the worst in decades in many places—especially in Texas, where gas outages have left millions without heat for days. At least 226 deaths and at least $26 billion in damage can be directly attributed to the cold wave, according to NOAA.Impact may be much bigger When considering the knock-on effects on the regional economy.

As if to make up for lost time, the country moved into warmer regions starting in March. Since then, each time interval that stretches into December (March-Dec, April-Dec, May-Dec, etc.) ends up being the hottest time in the country on record for that time period.

Severe heat and drought lead to yet another summer of destructive bushfires in the west, smog far east of the country in July. According to the National Interagency Fire Center, Total area burned annually in the U.S.2021— 7.13 million acres – Well below the 10 million-plus acres consumed in 2020, 2017, and 2015, and 8.7 million in 2018, although well above the 4.6 million in 2019. The largest fire that year, and the second largest in modern California history, was the Dixie Fire, which swept through 963,000 acres in July. The Dixie and Caldor fires each destroyed more than 1,000 structures in California.

The most tragic heatwave of the year, arguably the most unusual in modern global history, hit the Pacific Northwest in the United States and Southwest Canada in late June and early July. Seattle and Portland set record highs of 108°F and 116°F, respectively, on June 28. A total of 310 U.S. locations set or matched all-time highs in June.

early estimates Shows more than 600 heatwave deaths in Washington and Oregon, and more than 400 in British Columbia. Once researchers comb through death certificates and other evidence, they may find the final death toll is even higher.Team from the World Weather Attribution Project estimated Heat waves are about a once-in-a-millennium event, which would be “almost impossible” without human-caused climate change.

After an unusually mild fall, December 2021 is amazingly warm Over large areas, especially the Southern Plains and the lower Mississippi Valley, many places soared to above 70°F or even 80°F for multiple days. as mentioned Independent weather researcher Maximiliano Herrera said Houston’s average December temperature (both highs and lows) of 67.8°F was not only higher than any other December on record, but Higher than any November!

Likewise, Wichita Falls, Texas, to 91°F On Christmas Eve (Dec. 24), it melted December’s all-time high and surpassed any day in November.

Preliminary data from the US National Oceanic and Atmospheric Administration for December showed a total of 6,321 daily record highs and 910 monthly record highs were broken or tied nationwide.

Untimely Destruction in December

While there are clear benefits to December’s generally warmer — from reducing heating bills to promoting outdoor activities during the pandemic — a sustained record warm air mass, combined with ample low-level moisture from the tropics, has laid the foundation for the atmosphere Two devastating tornadoes erupted.

the first, in December 10-11, was the deadliest and potentially most destructive of any December on record nationwide, killing at least 90 people, mostly in western and central Kentucky, and confirming a record 69 tornadoes. NOAA estimated the loss at $3.9 billion.

Then, on Dec. 15, a massive hurricane swept across the central US, producing an EF2 tornado—outburst—in Minnesota and northern Wisconsin Unprecedented December in its northbound extent and total confirmed tornadoes. A total of 100 tornadoes made it one of the largest single-day outbreaks on record for any time of the year and shattered the December record set five days earlier.

The Dec. 15 tornado and widespread strong winds caused about $1.8 billion in damage, according to NOAA.

Unusually cold air gathered in western Canada, and a strong polar jet stream poured over the Rocky Mountains, leading to a violent mountain wave storm in and around Boulder, Colorado on December 30, with gusts of wind on the Rocky Plains reaching 115 mph. Winds have swept across terrain drier from record dry and near-record warm conditions since September. A wildfire swept through the towns of Louisville and Superior, east of Boulder, shocking residents and sending them fleeing. The fire was Colorado’s most destructive on record and the country’s most destructive winter wildfire on record, destroying 1,084 homes and killing at least 1 person (see our post from January 4th).

moisture and lack of it

Typically, average precipitation by state and year-round is a mixed bag for the U.S. Montana had its ninth driest year on record, while Massachusetts had its ninth wettest.

Clearly, the country has moved away from the wetness that was common a few years ago, when the country’s Wettest 12 months on record Record (37.93 inches from July 2018 to June 2019).

According to the U.S. Drought Monitor, from November 24, 2020 to November 16, 2021, extreme drought to abnormal drought covered more than 20% of the country for a total of 41 weeks. Since the inception of the monitoring station in 2000, no other 12-month period has covered such a wide range of extreme to exceptional droughts for such a long time.

Despite the extent and intensity of the 2021 U.S. drought, several devastating flooding events have been recorded, including flash flood On the morning of Aug. 21, 20 lives were lost in and around Waverley, Tennessee, after a “training” thunderstorm complex poured hours of heavy rain.

As Jeff Masters in his 2021 Hurricane Season Roundup, eight named storms made landfall in the United States in 2021, the third-highest total on record, after 2020 (11) and 1916 (9). During the 2020-2021 biennium, there were 19 landings in the continental United States, six times the average for the two-year period and surpassing the previous record of 15 landings set in 2004-2005.

Category 4 Hurricane Ida is the most destructive of any U.S. landfall in 2021. Ida struck Louisiana on August 29, making landfall at the port of Furchon, an important center for the oil industry, with 150 mph winds. Almost half of the houses on Grand Island were almost or completely destroyed. Ida brought more trouble after it weakened into a post-tropical cyclone and moved into the mid-Atlantic and northeast, bringing heavy rain. The New York City area was hit particularly hard, with Ida arriving days after Tropical Storm Henry caused flooding.

All told, Ida killed at least 96 people and cost an estimated $75 billion, the fifth-highest cost of any tropical cyclone in NOAA’s billion-dollar database.

Other landfalls to cause billions of dollars in damage to the U.S. in 2021 (mostly from flooding) are Tropical Storm Elsa (July, $1.6 billion), Tropical Storm Fred (August, $1.3 billion), and Hurricane Nicholas (September, $1 billion).

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