Historic Dec. 15 storm classified as first serial Derecho recorded in December

LA CROSSE, Wis. (WKBT) — Severe storms and strong winds Wednesday and Thursday were a rare occurrence in December. Another label assigned today adds to its rarity.

The National Weather Service is calling that storm event a serial Derecho. Derechos have to have at least 58 mph winds, with damage extending over 250 miles.

“It was a long lived line of thunderstorms that had, again, a lot of reports of very strong winds: 70-90 miles per hour,” said Todd Shea of the La Crosse National Weather Service. “Then we had these embedded tornadoes that made the impact greater and the challenge of warning greater.”

This is the first time on record that a Derecho has occurred in December

“It was a very historic and rare storm for December,” Shea said. “You know, when you take record warmth in the middle of December, and you add just a very strong weather system. It had a lot of energy with it, a lot of wind.”

“It’s unheard of in Decemeber, first derecho for the country in the month of December,” said Bill Graul, News 8’s chief meteorologist. “And the single largest tornado outbreak for our area for any time of year, let alone the month of December.”

On Wednesday, News 8’s viewing area saw at least 10 tornadoes. And there might be more. Typically, tornado assessment takes only a couple of days.

“We’re on, what? Day five? I guess we could say. We still have people out right now assessing more damage in the area,” Shea said.

Wednesday’s record high temperatures added still another element to the rarity. This is the latest derecho on record in the United States. Though this has never happened here before, Shea says there’s always a chance it could happen again.

The NWS is still surveying. You can find the most up-to-date information on those tornadoes on the national weather service’s website.

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