U.S. Severe Weather Outbreak

Updated Summary | Summary
Posting Date: December 13, 2021, 12:30:00 PM

Late on Friday, December 10, more than 33 tornadoes were reported in at least six states: Arkansas, Illinois, Kentucky, Mississippi, Missouri, and Tennessee.

ALERT™ subscribers may download two files from the Downloads tab, which can be used separately or in tandem to help understand impacts from this event. The first is a list of impacted ZIP Codes based on the locations of NWS Storm Prediction Center reports of tornado or possible tornado activity December 10-11; every ZIP Code in this file had at least one report of tornado activity during this time period. It should be noted that there may be areas that were impacted by tornado activity but are not included in this file because no report was made.

The second file provided for download is a shapefile of estimated tornado tracks and extents from Verisk Weather Solutions’ Respond®. The Respond Tornado solution provides a first estimate footprint of possible tornado-impacted locations. The solution creates a footprint for any reported tornado the morning after the event by tracking each storm's rotation through its life cycle. Given that, the current tornado solution may cover an area that is larger than where the actual tornado impacted. 

Most of the destruction came from just two tornadic storms. One of them traveled across the north of the St. Louis metropolitan area in Missouri and Illinois. The first tornado from this cell was given a preliminary rating of at least EF-3 and caused the partial roof collapse of an Amazon warehouse in Edwardsville, Illinois. One hundred miles south, a particularly long-lived—perhaps record-breaking—supercell thunderstorm spawned at least one tornado that tracked from northeast Arkansas, across southwest Missouri, northwest Tennessee, and western Kentucky. It is estimated that hundreds, if not thousands, of homes and businesses in and along the track across these four states were destroyed or partially damaged. According to radar, debris was hurled as high as 37,000 feet in some locations, indicating a particularly violent storm.

Fourteen people have been reported killed across four states: Arkansas (2), Illinois (6), Missouri (2), and Tennessee (4). The death toll in Arkansas is attributed to one who died in a nursing home in Monette, and one who died in a store in Leachville; the death toll in Illinois can be attributed to workers in an Edwardsville. The death toll estimate has fluctuated in Kentucky, as it is heavily dependent on how many were able to be rescued from the Mayfield Consumer Products candle factory. While the outlook was initially grim, with 110 people thought to be inside and perhaps only 40 rescued, more workers may have escaped death than previously thought. It is thought now that 90 people made it out of the factory alive.

Damage surveys are ongoing across a number of National Weather Service offices at this time, to better understand the scope and impact of these events. Following is a summary of the findings by these surveys:

From the Paducah, Kentucky, office:

• A historic long track tornado entered western Kentucky shortly before 9:00 p.m CST, tracking toward and through Cayce, continuing northeast through Mayfield, where it produced widespread destruction. After moving through Mayfield, the tornado passed through Benton and across the Land Between the Lakes. The tornado then continued near Mortons Gap before reaching Beaver Dam.

From the St. Louis, Missouri, office:

• In Edwardsville, Illinois, EF-3 damage reported west of Sand Rd., including the Amazon facility that was destroyed. East of Sand Rd., damage was rated at EF-1.
• Near Defiance, Missouri, EF-3 damage was reported and two homes were destroyed, along with damage to several outbuildings and other structures.
• EF-1 damage reported near Sorento, Missouri, and east of Donnellson, Missouri.
• EF-1 damage was reported between Country Road 440 and the town of Ellington, Missouri. Once crossing County Road 447, EF-2 damage was noted along County Road 442. After crossing the Black River, additional EF-1 damage was noted along County Road 456.

From the Nashville, Tennessee, office:

• EF-2 damage in Stewart County between the Tennessee River and the Fort Campbell Army base.
• EF-2 damage in Dickson just north of I-40.
• EF-2 damage was noted north of I-70 near White Bluff, Kingston Springs, and Pegram.
• EF-1 damage along Highway 13 and just north of I-40 in Humphreys County.
• EF-1 damage near Cooks Landing Court in Davidson County and in Mount Juliet, in Wilson County.

From the Little Rock, Arkansas, office:

• EF-2 damage affected areas from just north of Augusta (Woodruff County) to south of Tupelo (Jackson County). Homes and farm buildings were roughed up, and this resulted in three injuries. The other tornadoes (both rated EF-1) were brief and spun up to the southwest of Beedeville (Jackson County) and on the north side of Diaz (Jackson County).

Based on radar and initial damage reports, especially from Mayfield, an EF-4 may have occurred. It will take days for the National Weather Service to assess. One of the markers of EF-5 damage is a well-constructed home being destroyed and completely removed from its foundation. Naked slabs have been reported in Mayfield, but whether the destroyed buildings were well built and well anchored has yet to be determined.

On Sunday, December 12, President Joe Biden declared a major federal disaster in Kentucky. He will visit the affected area when it is prudent for him to do so. 

Hundreds of thousands of customers in the states affected were without power on Saturday, but now Kentucky has more than 25,000 without power and Tennessee about 7,500 without power.

Although tornadoes are not as common in December, they can occur any time of year. Tornado activity peaks from April through June. In March it generally ramps up significantly, and the month can see twice as many tornadoes as February. May is the top month for tornado touchdowns in the U.S. with an average of 276 for the period 1996–2015. This year got off to a strong start in terms of tornadoes. Although it is far too soon to know for sure how or whether climate change may have played a role in this outbreak, recent studies have shown that strong convective storms have been occurring earlier and later in the year than in the past because warmer conditions that typically exist during the warm season are more likely to coincide with stronger vertical shear that exists during the cold season.

AIR will continue to study this event in the coming days, however, no additional ALERTs are currently planned.

Updated Summary | Downloads
Posting Date: December 13, 2021, 12:30:00 PM

The information provided herein is strictly confidential and is solely for the use of AIR clients; disclosure to others is prohibited.

Additional Downloads

Note: Please use the appropriate application to view these files.

Title	File Type	Description	Download
Respond Estimated Tornado Footprints	.shp	A shapefile of the estimated tornado extents from December 10-11 from Verisk Weather Solutions Respond product.
List of Tornado Impacted ZIPs	.xls	A list of affected ZIPs based on SPC tornado reports over December 10-11.