Why tornado alley is shifting east

Supercells are projected to become more numerous in the eastern United States while decreasing in occurrence over the Great Plains. This has shifted the tornado alley map east.

Open up any science textbook, and it will likely show a map of the U.S. with the Plains highlighted as tornado alley, but according to research by Northern Illinois University, storms are now targeting areas further east, putting greater populations at risk.

An average year will produce over 1,200 tornadoes that result in hundreds of millions of dollars of damage across the U.S.

The twisters usually form when moisture from the Gulf of Mexico streams northward and enters the collision zone between warm and cold air.

Winds in the circling funnels of terror can top 200 mph and rip away homes and businesses, leaving behind only the foundations.


Dr. Walker Ashley, a meteorology professor at NIU, has been researching extreme weather and its impact on society for years and said his team has observed concerning data on who is most at risk for supercells.

"We’re seeing more conducive tornado environments in the east than what we see in the Central Plains. The research that we just completed suggests that this trend is going to continue," Ashley told FOX Weather.

An eastward shift of the severe weather threat zone puts areas of the Mid-South and Ohio Valley at more of a risk of seeing supercell development, which could result in greater populations experiencing hail, heavy rainfall, gusty winds and tornadoes.

"This has important consequences when it rolls through communities, whether it be an urban core of a city or a small rural community, much like we saw, for instance, last December in Mayfield, Kentucky," Ashley said.

The 2021 severe weather outbreak produced more than 70 tornadoes, with the strongest being an EF-4 that was on the ground for more than 165 miles.

The storm system was well forecast and warned, but it impacted higher population centers than it would have if the outbreak had occurred further to the west.

The tornadoes produced estimated damage of around $4 billion and caused nearly 100 fatalities. 


"If we really want to call tornado alley, you know, the occurrence and the footprint of actual tornadoes on the ground that would actually be in Arkansas, Tennessee, Alabama and Mississippi. And we certainly are finding in our research that these supercell storms are becoming going to become more frequent in this corridor that already has some heightened activity," Ashley said.

The researchers at NIU said they were able to pick up on the trends through the use of a supercomputer from the National Science Foundation and better able to define when tornado alley really exists.

Using data from past events and projecting out years into the future, the team picked up on subtle eastward shifts, which could continue for centuries due in part to the ever-changing climate.