Tornado outbreak of December 10–11, 2021

A deadly late-season tornado outbreak, the deadliest on record in December, produced catastrophic damage and numerous fatalities across portions of the Southern United States and Ohio Valley from the evening of December 10 to the early morning of December 11, 2021. The event developed as a trough progressed eastward across the United States, interacting with an unseasonably moist and unstable environment across the Mississippi Valley. Tornado activity began in northeastern Arkansas, before progressing into Missouri, Illinois, Tennessee, and Kentucky.

The most prolific activity was caused by a long-track supercell thunderstorm that produced a family of strong tornadoes that travelled across four Mid-South states. The first of these nocturnal tornadoes, a low-end EF4, touched down in northeastern Arkansas, near Jonesboro and tracked through the Missouri Bootheel, ripping through towns such as Monette and Leachville, Arkansas, and Hayti and Caruthersville, Missouri. After crossing the Mississippi River into northwestern West Tennessee, that tornado dissipated, and a high-end EF4 tornado formed and moved through Western Kentucky, where the towns of Cayce, Mayfield, Benton, Princeton, Dawson Springs, and Bremen suffered severe to catastrophic damage.

Early estimates suggested that the tornado family identified by some media outlets as the "Quad-State tornado," due to the storm's similar characteristics to the Tri-State tornado that occurred 96 years prior may have cut a path of up to 250 miles (400 km) across the affected areas. If it had been a single tornado, it would have surpassed the March 18, 1925, tornado event (which carved a 219-mile [352 km] path across Missouri, Illinois, and Indiana) in terms of path length. However, storm surveys found that the path was predominantly composed of two distinct EF4 tornadoes, with the portion of the path between them over northwestern Obion County, Tennessee being from three separate, weak tornadoes. Other tornadic thunderstorms affected portions of eastern Missouri, southern Illinois, West and Middle Tennessee, and Western and Central Kentucky during the late evening into the overnight hours of December 11, including four intense tornadoes that hit Bowling Green, Kentucky; Dresden, Tennessee; Edwardsville, Illinois; and Defiance, Missouri. This included a second supercell and tornado family, which produced an EF3 tornado tracking nearly 123 miles (198 km) in Tennessee and southern Kentucky, as well as numerous tornadoes, including three more rated EF3, throughout southern and central Kentucky.

The death toll from the outbreak was 89 (with three additional non-tornadic fatalities), surpassing the Vicksburg, Mississippi tornado of December 5, 1953, which caused 38 fatalities, as the deadliest December tornado event ever recorded in the United States. In Kentucky alone, at least 75 people were killed. At least 55 people were injured, with the number of injuries from the long-track EF4 tornadoes, the Bowling Green EF3 tornado, and the Edwardsville EF3 tornado currently unknown.

## Meteorological synopsis

The Storm Prediction Center (SPC) first delineated a slight risk of severe weather along much of the Mississippi Valley on December 8. Despite the potential for a higher-end severe threat to materialize, forecasters expressed uncertainty regarding the extent of instability, degree of directional wind shear, and late timing of potential storms. The following day, the SPC discussed higher certainty in a corridor of organized severe thunderstorm potential stretching from southeastern Arkansas northeast into southern Indiana, upgrading that region to an enhanced risk. As an intense upper-level trough progressed across the High Plains, with robust instability and moisture return realized across the Mississippi Valley, the SPC expanded the enhanced risk and introduced a moderate risk area from northeastern Arkansas into southern Illinois on the morning of December 10. Forecasters indicated that atmospheric conditions favored the development of nocturnal supercells capable of producing long-tracked, strong tornadoes.

At 3:00 p.m. CST (21:00 UTC), the SPC issued a tornado watch across the highest risk area (encompassing central and eastern Arkansas, west Tennessee, northwestern Mississippi, southeastern Missouri, and southern portions of Illinois and Indiana), the first of eleven issued over subsequent hours over the middle Mississippi Valley. Initial storms developed across central Arkansas around 2:00 p.m. CST (20:00 UTC), with even weaker activity developing over central Missouri a little over 1+1⁄2 hours later; additional clusters of thunderstorms developed over southwestern Missouri (forming between Bolivar and Carthage, eventually backbuilding into northeastern Oklahoma) and central Arkansas (forming southwest of Hot Springs) between 5:00 and 5:30 p.m. CST (23:00–23:30 UTC). Though this activity lacked much vigor at its onset, the convective cells began to show organization as they progressed eastward.

One such storm—which formed from the initial mid-afternoon activity near Arkadelphia, Arkansas—matured into a long-lived supercell as it progressed in an unstable, deeply moist, and highly-sheared environment; this cell ultimately persisted for 250 miles (400 km) over several hours from eastern Arkansas into Kentucky, producing multiple large and intense tornadoes along its track. The cell began exhibiting surface-based rotation southwest of Searcy, Arkansas around 5:30 p.m. CST (23:30 UTC). At 5:51 p.m. CST, the National Weather Service office in North Little Rock issued the first tornado warning associated with the storm for portions of Jackson, Lawrence, White, and Woodruff counties. One of the first tornadoes associated with the storm, an EF0, touched down in western Poinsett County (near Weiner) around 6:40 p.m. CST; about fifteen minutes later, storm spotters reported a large tornado near Greenfield, prompting a PDS tornado warning for portions of Poinsett, Craighead and Mississippi counties (including areas to the south of Jonesboro).

Doppler radar analysis estimated that the supercell maintained a nearly continuous high-end rotational vorticity signature, averaging at 94 mph (82 kn) for approximately four hours and 20 minutes, among a rarity of thunderstorms (averaging 1.5% of all supercells) that produce mesocyclonic vorticity exceeding such speeds. (The only velocities below said average recorded along the storm track, sustained between 75 and 81 mph [65–70 kn], were observed from 8:44 to 9:01 p.m. CST [02:44–3:01 UTC] during an apparent mesocyclone recycling phase as the storm crossed from Obion County, Tennessee into Hickman County, Kentucky.) Peak gate-to-gate velocities of 128 mph (111 kn) were recorded at 9:58 p.m. CST (04:58 UTC) over northeastern Marshall County, Kentucky.

Elsewhere, multiple lines of intense storms, some featuring embedded supercells, developed across the Mississippi Valley region through the overnight hours, contributing to additional strong and long-lived tornadoes. By the pre-dawn hours of December 11, a decrease in instability led to a gradual weakening of a line of thunderstorms stretching along the associated cold front from eastern Kentucky southward into central Alabama.

The SPC issued a record-setting 43 mesoscale discussions (MCD) throughout the course of the day (12 UTC December 10 to 12 UTC December 11), all of which were associated with the broader storm system: 38 of the MCDs issued were convective discussions relating to the severe thunderstorm activity, and five were non-convective discussions relating to heavy snow associated with the system that concurrently fell throughout much of the Upper Midwest. The National Weather Service (NWS) issued a total of 149 tornado warnings throughout the night across portions of nine states including Arkansas, Tennessee, Missouri, Mississippi, Kentucky, Illinois, and Indiana.

Multiple PDS tornado warnings and tornado emergencies were also issued as well in Arkansas, Tennessee, Kentucky, and Missouri. Eight of the tornado warnings issued during the event by the NWS offices in Memphis, Tennessee, and Paducah, Kentucky were tornado emergency declarations, the most issued during the month of December (breaking the previous record of three issued on December 23, 2015).

Effects from the system responsible for the outbreak extended into Canada, where the Meteorological Service of Canada issued wind and heavy rainfall warnings for portions of Ontario. However, no tornadoes were expected or reported north of the border.

## Confirmed tornadoes

Confirmed tornadoes by Enhanced Fujita rating

### Monette, Arkansas – Reelfoot Lake/Samburg, Tennessee

Monette, Arkansas – Reelfoot Lake/Samburg, Tennessee

The first major long-track tornado of the outbreak, rated low-end EF4, touched down in Craighead County, Arkansas, just north of Bay, at 7:07 p.m. CST (01:07 UTC) on the evening of December 10. The tornado quickly intensified to EF2-strength as it passed northwest of Lake City. It grew to a width of 800 yards (730 m) as it tracked northeast into Monette at 7:23 p.m. CST (01:23 UTC). The Monette Manor nursing home was struck by the tornado, killing one person and trapping 20 other residents and employees. Five people were reported seriously injured. State Highways 135 and 139 were also shut down near the town due to downed power lines on the roadways.

The tornado crossed into northwestern Mississippi County, entering northern sections of Leachville at 7:30 p.m. CST (01:30 UTC); there, it destroyed a local Dollar General, where a woman (who served as the store's assistant manager) was killed. The tornado crossed the state line into Dunklin County in the Missouri Bootheel at 7:40 p.m. CST (01:40 UTC), passing south of Hornersville and over the Hornersville Swamp Conservation Area. About 15 minutes later, it crossed into Pemiscot County west of Steele. As it crossed Interstate 55 just south of Hayti, the wedge tornado overturned several semi-trailer trucks. In Braggadocio, a nine-year-old girl was killed, and her parents and two younger sisters were injured when their home was damaged by the tornado; at least nine people overall were injured in the county.

East of Hayti, the tornado then crossed the Mississippi River into Lake County, Tennessee around 8:20 p.m. CST (02:20 UTC). It briefly crossed a bend in the river back into Missouri before crossing into Lake County again. Moving through central Lake County, the tornado narrowly missed the small community of Wynnburg, while passing a couple miles south of Tiptonville. Northeast of Wynnburg, the tornado reached Reelfoot Lake, striking Cypress Point Resort and resulting in three fatalities. The tornado crossed the southeast part of the lake, entering Obion County and hitting the town of Samburg, resulting in heavy damage along Highway 22. Northeast of Samburg, the tornado began to weaken, with the roof being blown off a building along Old Samberg Rd. It continued northeastward along the road until it dissipated approximately 2.5 miles (4.0 km) northeast of Samburg at 8:36 p.m. CST (02:36 UTC), having been on the ground for 89 minutes and 81.2 miles (130.7 km) and reaching a maximum path width of 1,800 yards (1,600 m).

Three deaths were confirmed by officials at the Obion County Emergency Management and Tennessee Emergency Management Agency the day after the tornado: one in Obion County and two in Lake County. A fourth fatality was confirmed in the Reelfoot Lake area after a missing person from Cypress Point was recovered a few days later, bringing the total in Lake County to three. Multiple serious injuries were also reported at a mobile home park in Samburg and at a resort. Samburg was reported to be "pretty well flattened" by the Obion County Sheriff's Office dispatcher.

After the tornado dissipated, the parent supercell entered a cycling phase, producing three brief tornadoes, one EF1 and two EF0s, in Obion County northeast of Samburg and west of Union City. As the storm passed to the northwest of Union City, it produced a stronger, longer-tracked tornado near Woodland Mills.

### Edwardsville, Illinois

Edwardsville, Illinois

A tornado touched down northeast of Pontoon Beach in Madison County, Illinois, on the northwest side of the intersection of Interstates 255 and 270, at 8:28 p.m. CST (02:28 UTC) on the evening of December 10. The tornado grew to a width of 300 yards (270 m) and quickly intensified to EF3 strength as it tracked northeast toward Edwardsville. It struck an Amazon warehouse, where night workers were beginning their shifts and several employees were attending a Christmas party being held as the tornado approached the town. Six people were killed when the west-facing walls of the structure collapsed inward, causing cascading structural failure to walls and a large section of the roof. Drone footage showed a partially collapsed roof and a gutted interior. Employees were told to shelter in bathrooms.

Between 50 and 100 people were trapped in the intact remnants of the warehouse; about 30 people were brought to the Pontoon Beach police station in a bus for further evaluation. One person was air-flown via helicopter to a hospital. The tornado blew the roof of the building off, and a 100-foot (30 m) wall also collapsed.

Cars at the facility were thrown eastward, while power lines and several large high-tension towers were destroyed. Elsewhere, an unanchored mobile home and an outbuilding were destroyed, while houses suffered more superficial damage. Trees were downed along the short 3.65-mile (5.87 km) path before the tornado dissipated at 8:32 p.m. CST (08:32 UTC)

### Mayfield–Princeton–Dawson Springs–Bremen, Kentucky

Western Kentucky

Main article: 2021 Western Kentucky tornado

After the original long-track tornado dissipated over western Obion County, Tennessee, the associated supercell underwent a brief mesocyclone cycling phase and spawned a new long-track tornado in northern Obion County near Woodland Mills at 8:49 p.m. CST (02:49 UTC). The tornado crossed into Kentucky near the community of State Line and struck Cayce at about 9:00 p.m. CST (03:00 UTC), where at least EF3 damage was observed to homes, businesses, and the town’s fire station and a local school; one person was killed in the town. It then moved northeast through rural communities in Fulton and Hickman counties.

Closely paralleling Interstate 69 and U.S. 45 into Graves County, the tornado moved directly toward Mayfield, entering the southwestern portion of the city at 9:25 p.m. CST as it reached EF4 intensity. One minute later, at 9:26 p.m. CST, the National Weather Service office in Paducah issued a tornado emergency for Mayfield. Radar analysis indicated that the tornado had lofted debris up to 30,000 feet (9,100 m) into the air as it ripped through and to the northeast of the city. Most of the structures in downtown Mayfield were either heavily damaged or destroyed. Serious damage occurred to several structures in the Mayfield Downtown Commercial District, including the city hall. The Graves County Courthouse suffered significant roof damage, had its clock tower torn off, and had some of its exterior upper-floor walls knocked down. The fire station and police station in the city were also destroyed, and the town's water tower was toppled to the ground and ripped to pieces. The town's emergency operations center lost the ability to transmit radio communications. Search and rescue teams in the wreckage of a candle factory in Mayfield on December 13, 2021 About 110 people reportedly were trapped at the Mayfield Consumer Products candle factory when the tornado hit the facility; by the evening of December 12, eight people had been confirmed dead and eight others remained missing. By the next day, all employees from the factory had been located. Allegedly, workers' jobs were threatened if they left the factory between the first and second tornado warnings for the area, and then again after the second tornado warning sounded. The candle factory's emergency protocols are pending investigation by state authorities. Kentucky Governor Andy Beshear stated that over 50 people died in the city during a live phone interview with Louisville CBS affiliate WLKY on December 11. He later upped his estimate to 70 people, and also said that the death toll could rise to over 100 across the entire state. Officially, at least 20 people have been confirmed to have died from the tornado in Mayfield.

The tornado’s projected path towards several densely populated towns prompted the National Weather Service’s Paducah office to issue additional tornado emergencies over the next two hours for the towns of Benton, Princeton, Dawson Springs, Earlington, and Bremen. Continuing northeast along I-69 into Marshall County, it continued to produce major damage as it struck the northwest side of Benton around 9:45 p.m., and into the lakeshore community of Cambridge Shores at 9:56 p.m. After passing over the southeast side of Princeton, the tornado moved into Dawson Springs around 10:30 p.m. CST; there, up to 75% of the city suffered heavy damage. At least 13 people died from the tornado in Dawson Springs; a two-month old baby was taken off life support two days after the tornado hit. One of the pieces of debris lofted as the twister barreled through town, a photograph from 1942, was transported for almost 130 miles (210 km) by the intense tornadic updrafts, and was eventually found in New Albany, Indiana. Four additional fatalities were caused by the tornado in surrounding areas of Caldwell County.

In unincorporated Barnsley (near Earlington), the tornado derailed a CSX freight train, knocking over 25 of the train's freight cars, and sweeping one car lofted by the funnel into a nearby home. No casualties were reported. In Bremen in Muhlenberg County, the tornado destroyed many homes and downed a large number of trees in the town. At least 12 people were killed there, with victims ranging between the ages of 5 months and 75 years. Among the fatalities was District Judge Brian Crick, who represented Muhlenberg and McLean counties, as confirmed in a statement from the Supreme Court of Kentucky on December 11. Multiple residents suffered injuries that required medical attention.

Crossing into Ohio County, the tornado passed just north of Centertown and Hartford, crossing U.S. 231, Interstate 165 and the Rough River. Areas of EF3 damage were observed near Hartford, where several homes were destroyed. The tornado crossed the Rough River a total of eleven times in Ohio, Grayson and Breckinridge counties, producing EF1–EF2 damage to structures along its northeastward track. After crossing the river for a final time northeast of Falls of Rough, it re-entered Grayson County, moving into Rough River Dam State Resort Park before dissipating near Rough River Lake, approximately four miles (6.4 km) west of McDaniels at 11:47 p.m. CST (5:47 UTC). The tornado was on the ground for nearly three hours, with a path length of 165.65 miles (266.59 km), a Kentucky state record and one of the longest continuous paths in recorded history.