A widespread, deadly, and violent tornado outbreak slams the Central, Midwestern, and Southern regions of the United States. Eighty-nine people are killed by the tornadoes, with most of the fatalities occurring in Kentucky, where a single tornado kills 57 people, and injures hundreds of others.

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 the 11th, 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 Central United States is sometimes conceived as between the Eastern and Western as part of a three-region model, roughly coincident with the U.S. Census Bureau's definition of the Midwestern United States plus the western and central portions of the U.S. Census's definition of the Southern United States. The Central States are typically considered to consist of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Minnesota, Iowa, Missouri, Arkansas, Louisiana, Wisconsin, Illinois, Michigan, Indiana, Ohio, Kentucky, Tennessee, West Virginia, Mississippi and Alabama.

The Midwestern United States is one of the four census regions defined by the United States Census Bureau. It occupies the northern central part of the United States. It was officially named the North Central Region by the U.S. Census Bureau until 1984. It is between the Northeastern United States and the Western United States, with Canada to the north and the Southern United States to the south.

The Southern United States is one of the four census regions defined by the United States Census Bureau. It is between the Atlantic Ocean and the Western United States, with the Midwestern and Northeastern United States to its north and the Gulf of Mexico and Mexico to its south.