A dark sky tightened into forbidding swirls over northern Kansas on Tuesday, unleashing the year’s first rash of tornadoes in the central United States. More than a dozen were reported across the state and neighboring Oklahoma, ending the “tornado drought” of 2018. To the residents of America’s Tornado Alley, making it this far into the spring without having to escape a strong twister is somewhat unusual indeed.
As the Wichita Eagle reported on Wednesday, Kansas has not made it to May without a tornado since 1980, and as far as anyone can tell, it’s never happened in Oklahoma. But after the drought comes the flood, and both states, as well as Nebraska and Iowa, are bracing themselves for more tornadoes and severe storms in light of reports from the National Weather Service. The institution’s Storm Prediction Center announced a Public Severe Weather outlook for the region on Wednesday: “Swaths of damaging winds, large to very large hail, and several tornadoes will be possible, especially from northwest Missouri across central Kansas to northwest Oklahoma.”
Sounds scary, but Tornado Alley is used to this kind of thing. By virtue of its flatness, it’s the perfect meeting ground for cold, dry polar air from Canada to crash into warm, moist tropical air from the Gulf of Mexico. This dangerous combination encourages the formation of supercell thunderstorms, which in turn are implicated in the formation of tornadoes graded EF-2 or higher (the highest is EF-5, which any Twister fan will remember is utterly terrifying). “The tornadoes are being caused by supercell storms that are being driven by the strong wind shear,” reiterated Chris Broyles, a meteorologist with the service’s Storm Prediction Center, in an interview with Reuters on Tuesday.
What’s unusual is that it took this long for very strong tornadoes to form. Usually, they strike in Tornado Alley in late spring and sometimes in the early fall. A separate ‘tornado drought’ had actually occurred last year. “[The] last 269 days of 2017 and 2018 have been relatively quiet. With no EF-3 or stronger tornadoes in that time period (and counting), this makes it the longest EF-3+ tornado drought dating back to 1953,” Weather Network meteorologist Jaclyn Wittall reported in February. She explained that the polar air was traveling too far south, bringing extreme cold to the entire U.S. but preventing the warm air from the Gulf of Mexico from meeting halfway.
If tornado season’s dates continue to shift over the next few years, it’ll likely draw the attention of climate change researchers, who are currently not sure about the connection between tornadoes and the changing climate. “It is likely that a warmer, moister world would allow for more frequent instability,” write researchers with the Center for Climate and Energy Solutions. “However, it is also likely that a warmer world would lessen chances for wind shear.”
For the present, however, the Tornado Belt better brace itself: According to a report from AccuWeather on Wednesday, the current storm-causing confluence of warm and cool air is slowly being pushed eastward by a press of cool air, which won’t dissipate until this weekend.