On December 10, a cluster of more than 30 tornadoes spun through Arkansas, Illinois, Kentucky, Missouri, Mississippi, and Tennessee. Amid 250 miles of destruction, more than 100 people are feared dead after storms ripped through businesses and residencies, per CNN.
The string of tornadoes may be the nation’s deadliest and most destructive in over a decade, Bob Henson for Yale Climate Connections reports. The Enhanced Fujita Scale is used to categorize tornadoes based on estimated wind speed and related damage. The winter tornadoes all earned strong-to-violent ratings between EF3 and EF5.
NEW: @NOAA's #GOES16tracked the fast-moving #severe thunderstorms that produced a devastating #TornadoOutbreak overnight. More than 30 #tornadoes were reported across 6 states. Kentucky's governor called it "the most severe and deadly tornado event in Kentucky history." #KYwx pic.twitter.com/wmZplFUP0j— NOAA Satellites - Public Affairs (@NOAASatellitePA) December 11, 2021
In Mayfield, Kentucky, alone, the death toll could be over 70. If the death toll exceeds 100, it would be considered among the nation’s top 15 deadliest on record, as well as the only tornado to have killed more than 80 people outside of tornado season, which occurs between March and June, per Yale Climate Connections.
In Kentucky, twisters whipped through several large buildings, including a candle factory that collapsed into a pile of debris, CNN reports. As of Sunday night, eight deaths at the candle factory were confirmed, and eight other individuals are yet to be found. The company’s spokesperson Bob Ferguson told CNN that more than 90 employees escaped the factory safely.
In Illinois, six people were killed after a tornado crushed an Amazon warehouse in Edwardsville, CNN reports. As of Saturday night, 99,000 customers in Kentucky, and 71,000 in Tennessee were without power, reports Cheney Orr for Reuters. Tornadoes that tear through landscapes at night often cause the most fatalities because the twisting winds are difficult to guage in the dark, and people may not wake up when tornado warnings go into effect, NBC News reports.
One of these storms—dubbed the Quad-State Tornado—traveled more than 200 miles in four hours through northeast Arkansas, southeast Missouri, northwest Tennessee, and western Kentucky, report Kathryn Prociv and Nicole Acevedo for NBC News. The National Weather Service has yet to confirm whether all of the destruction was caused by a single twister or multiple tornadoes produced by the same storm. If one twister is confirmed as the cause, it sets a record for the longest continuous tornado path in U.S. history, reports Jeanna Bryner for Live Science.
Still in shock and awe at the longevity of the quad-state supercell last night. While this map shows approximate start and end times of the mesocyclone, most of it's life cycle had an extremely violent tornado, particularly between 1z and 5z. pic.twitter.com/Vnpx4ZSWBr— Alex Schueth (@ASchueth) December 11, 2021
What Caused the December Tornadoes?
A dynamic storm system rushing in from colder West and northern Midwest collided with record-breaking abnormally warm weather in the lower Midwest and South, report Alisa Hass and Kelsey Ellis for the Conversation. The warm air covering these states came from a La Niña weather event currently covering the United States.
Historically, La Niña has caused increases in tornado patterns across the Mississippi Valley, per NBC News. The severe thunderstorms and tornadoes were fueled by warmer than average weather in the Midwest. When the cold front interacted with warm air, it created unstable atmospheric conditions, perfect for tornadic supercell thunderstorms.
The weekend’s storms and abnormally warm weather may have been exacerbated by climate change. In the past, the area notoriously known as "Tornado Alley" was made up of states largely in the Great Plains, including Texas, Louisiana, Arkansas, Oklahoma, Kansas, South Dakota, Iowa and Nebraska. Previous research published in Nature in 2018 found that warming weather patterns may push Tornado Alley into parts of the Mississippi Valley, NBC News reports.
On average, December sees about 24 twisters in the United States per year. Tornadoes touching down as far north as Illinois and Kentucky are highly uncommon for early winter.