Ahh, late October. The time of year when the fall leaves are at peak color, the World Series is in play, Halloween candy is being devoured, and the second tornado season begins. “The what now? Aren’t tornadoes a spring thing?” you might be thinking. Yes. And no. Tornadoes can happen at any time of year, actually — even in winter — as long asMore
While parts of the western U.S. seem to have skipped ahead to winter, with snow blanketing areas from Washington to Colorado, unsettled weather more reminiscent of spring is in store early in the week for parts of the Southern Plains and South.
The spate of storms — sometimes including tornadoes — is a fairly typical feature of November. Fall, like spring, is a transitional season when warm, moist air masses clash with cold, dry ones, creating a recipe for severe weather. But officials are still urging residents to keep up-to-date with their local forecast and be aware of the possibility of strong winds, hail and tornadoes.
The potential for severe weather this week is a product of a strong jet stream and high wind shear — when winds blow in different directions at different levels of the atmosphere — meeting moist, unstable air surging in from the Gulf of Mexico.
— Matt Lanza (@mattlanza) November 16, 2015
The threat Monday is centered on western Oklahoma, the Texas Panhandle and parts of Kansas, while on Tuesday, the focus will shift to Louisiana, Arkansas, and parts of eastern Texas and western Mississippi, according to the latest forecasts from the National Weather Service’s Storm Prediction Center (SPC).
This bout of severe weather is the latest in a series of disturbances to move across the Plains, including one last week that brought tornadoes and then snow to the Des Moines area just six hours apart. This system is tracking a bit further south than some other recent ones, though, said SPC warning coordination meteorologist Greg Carbin, which means it has more moisture to potentially tap into.
The timing of the system’s progression increases the odds of nighttime tornadoes, which can be more deadly because people might be asleep when when warnings go out. The threat could come despite the system not benefitting from the additional instability that can come from the sun’s heating of the ground and lower levels of the atmosphere, which help dry daytime . The potency of the jet stream and other forces could be enough to overcome that limitation, Carbin said.
“Even very weak instability may be sufficient for damaging wind gusts and perhaps fast-moving nighttime tornadoes,” he said in an email.
— NWS Norman (@NWSNorman) November 16, 2015
These storms raise questions about the role of El Niño in driving severe weather across the Plains (and other parts of the U.S. and the world for that matter). Western Oklahoma and the Texas Panhandle actually tend to see more days with a tornado watch during El Niño’s cool counterpart, La Niña, but the Gulf Coast does have more during El Niño.
While the SPC has broadly identified the areas that are more likely to see severe weather, they can’t pinpoint in advance exactly when or where tornadoes or hail might strike. That can only be discerned when storms have formed and forecasters can monitor them via radar and weather spotters who can confirm sightings of tornadoes and other types of weather.
The bottom line they emphasis is to keep tabs on the weather in your neck of the woods.