'Tornado Alley' Has Shifted East From The Plains, A New Study Says

T​he nation's "Tornado Alley" has shifted and tornadoes are increasing in colder times of the year, a recently published study found.

T​he Deep South "Alley": Since the mid-1980s, tornadoes have been most numerous in the Deep South, including Mississippi, Alabama, Louisiana and Tennessee, according to a recent study by Timothy Coleman, Richard Thompson and former The Weather Channel severe weather expert Greg Forbes.

Published in the April 2024 issue of the Journal of Applied Meteorology and Climatology, the study examined tornadoes rated F/EF1 or stronger over two separate, 35-year periods (1951-1985 and 1986-2020) to look for changes in where these tornadoes formed. F/EF0 tornadoes were excluded to filter out the much greater number of these weakest tornadoes detected in recent years due to improved technology and more extensive National Weather Service damage surveys.

A​s the map below shows, a corridor of increased tornadoes extended from the lower Ohio Valley to the Deep South and westward to Oklahoma.

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What past decades looked like: From the mid-20th century until the mid 1980s, the map looked like the past version of the Plains "Tornado Alley" with peak activity from northern Texas into Oklahoma and Kansas.

What has changed most: The largest increase in tornadoes between the two 35-year periods has been from western Kentucky and the lower Ohio Valley to Mississippi and Louisiana.

Fewer tornadoes have occurred in recent decades in the Plains, from parts of Texas to Oklahoma, eastern Kansas and western Missouri.

T​he study says this change is "dispelling any misconceptions caused by the better visibility of tornadoes in the Great Plains vs. the eastern U.S."

S​easonal changes, too: There have also been important changes in when tornadoes occur.

Tornadoes have trended away from summer toward the fall and winter.

Summer tornadoes were 37% fewer from 1986 through 2020 than in the previous 35-year period. T​his summer reduction was most pronounced in the Plains, including parts of Oklahoma, Texas and Kansas.

But the largest increases occurred in fall (80%) and winter (102%), primarily in the Southeast, where they're most common that time of year.

T​he study also found the spring tornado maximum areas have spread through parts of the mid-Mississippi and lower Ohio valleys into the Deep South, instead of focused only in the Southern Plains.

What does it all mean? First, despite many previous research studies in past decades focused on the Plains, the tornado threat is often significant in many other locations, particularly the Deep South and Ohio Valley.

S​econd, while the nation's tornado count often peaks in spring, there really isn't a "tornado season", per se. They can occur at any time and anywhere conditions are favorable for the severe thunderstorms that spawn them.

This year, Wisconsin had its first February tornado on record, and that was followed by a rash of tornadoes from northern Illinois to New York state around the month's end.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. His lifelong love of meteorology began with a close encounter with a tornado as a child in Wisconsin. He completed a Bachelor's degree in physics at the University of Wisconsin-Madison, then a Master's degree working with dual-polarization radar and lightning data at Colorado State University. Extreme and bizarre weather are his favorite topics. Reach out to him on X (formerly Twitter), Threads, Facebook and Bluesky.