Sunday’s Wilson County tornado an example of a ‘non-supercell spin-up’

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WILSON COUNTY, Tenn. (WKRN) – The National Weather Service confirmed an EF-0 tornado touched down in western Wilson County Sunday afternoon. News 2 viewers sent in videos of the spin-up which formed near I-40.

Josh Barnwell, a lead forecaster at the NWS office in Nashville, says that Sunday’s tornado was weak and brief, and no structural damage occurred. Most tornadoes in Middle Tennessee are associated with powerful rotating thunderstorms called supercells. However, the tornado that touched down on Sunday was a non-supercell tornado.

Barnwell says that sunshine created just enough instability for rotation.

“The sun did come out and there’s a little bit more instability if that kind of environment can be created.”

It’s a phenomenon that Barnwell likens to a small-scale whirlwind.

“You can get these quick little spin ups kind of like when you’re walking down an alleyway and you see a paper bag spinning around.”

Non-supercell tornadoes are typically weaker and briefer than their supercell counterparts. Often this type of tornado is so brief that rotation is not picked up on radar.

“They’re usually on the weaker side, they’re not usually too much to worry about, especially, you know, if they’re out in the middle of nowhere, we might not see them,” says Barnwell. “But typically they don’t cause much damage. They’re very short-lived.”

While non-supercell tornadoes are uncommon in Middle Tennessee, they aren’t unheard of and are most likely to occur during the spring or fall months when there are greater differences in temperature.

“We can have days where the high temperatures are like 50, but then the sun can be out the next day and it could be like 70 or 80, so we’re kind of getting that hot-cold thing, you know, that mixture of air going in and if you get any kind of difference in heating you can kind of get a stronger environment. Even that little small area just to get these quick spin-ups.”

News 2 StormTracker

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