The term Tornado Alley can be traced back to the 1950s when two Air Force meteorologists used it as the title of a research paper about severe weather in Texas and Oklahoma.
Stretching from Texas northward into the Dakotas Tornado Alley, especially in the spring, sees warm, moist, unstable air traveling north from the Gulf of Mexico.
Cool dry air moving south from Canada, and strong upper-level winds speeding out of the rocky mountains to create tornadoes.
“This is still the part of the world where more violent tornadoes occur than any other place on the planet,” National Severe Storms Laboratory Senior Research Scientist Harold Brooks said.
But is that changing? In the early 1970s the term Dixie Alley was first used.
“That loosely defined extends from eastern Louisiana through Alabama,” Brooks said. “And it particularly seems to be focused on the fact that they get a lot of tornadoes in the fall.”
Brooks, at the National Weather Center in Norman, Oklahoma, and colleague Victor Gensini have been researching a shift in the alleys.
“And what we found is that the number of reports and the number of favorable environmental conditions have been increasing over the mid south over the last 40 years and have been decreasing over the western part of the plains and perhaps northwest Texas as well,” Brooks said.
So what’s causing it? Tempting to say global warming.
“Why is an interesting question,” Brooks said. “And it’s one where we don’t have a good answer. The fact that changes occur as the planet has been warming over the last 40-50 years it makes it very tempting to think that it is related to global warming but we don’t have a complete physical linkage yet to do that.”
If Texoma is trending down? Can we breathe a sigh of relief?
“I don’t think there is a particular sense of relief that you can get if you live in Texoma about any of the changes we’ve seen because the threat is still there,” Brooks said. “It’s still a real threat.”
Brooks said across our part of Tornado Alley the decrease in favorable tornado conditions is down only about 10 percent—so stay alert.