Tornado Alley moving east

Purdue University Photo A team member sets up to track severe weather activity. VORTEX Southeast is an effort to understand how environmental factors characteristic of the southeastern U.S. affect the formation, intensity and path of tornadoes in the region.

WEST LAFAYETTE — Tornado Alley, which currently stretches from Oklahoma to Texas, may be shifting to the east.

That relocation could affect Illinois and Indiana as Purdue University weather watchers sort out the impact.

"It probably is having an impact, although we have a lot more work to do to tease that out," Dan Dawson, an assistant professor of earth, atmospheric and planetary sciences at Purdue, said in an email response.

A 2016 study published in the Journal of Applied Meteorology and Climatology shows that from 1954 to 1983, the center of tornado activity was between southeastern Oklahoma and northeastern Texas. By 2013, it had moved to northern Alabama.

The tornado season is nearing its typical end in June 3. Already, there have been more than 130 reports of tornadoes across the U.S. in the last week. Although tornado deaths have been on the decline thanks to advances in scientific understanding of the storms and better warning systems, there's still a lot scientists don't know, Purdue researchers said.

In the spring of 2016 and 2017, Purdue researchers chased storms in northern Alabama as part of the VORTEX Southeast project. VORTEX Southeast is a study of environmental characteristics in the southeastern U.S. and their effects on the formation, intensity, structure and path of tornadoes.

"Most tornadoes, especially strong ones, are produced by a type of thunderstorm known as a 'supercell,'" Dawson said. "Some evidence suggests that tornadoes in the Southeast, while also often occurring in supercells, are produced more often than elsewhere from non-supercell storms. We hope to learn more about the nature of the formation processes for these tornadoes and how they differ from their supercell counterparts."

The Purdue team, comprised of Dawson, Ernest Agee, Michael Baldwin, Dan Chavas and Robin Tanamachi, is examining its research.

One study looked at the variables of small-scale terrain, such as hills, affect tornadoes in Arkansas. Based on empirical data from 1955 to 2015, researchers found that tornadoes are impeded by hills. The findings were published in the Journal of Applied Meteorology and Climatology.

"If hills are affecting tornadoes, are they interfering with them directly, on a physical level? Or are the storms that tornadoes form from, which occur on a slightly larger scale, not likely to form in areas with a lot of terrain variability?" said Chavas, who led the study. "We found that this phenomenon is occurring on a really small scale, so the tornado is being directly affected by the terrain."

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