On Dec. 15, 2021, a powerful storm system swept across Wisconsin, spawning multiple tornadoes across the state.

One year later, we look back at that historic storm and rare December tornadoes.

From 1950 to 2020, five tornadoes occurred in December in Wisconsin.

But on Dec. 15, 2021, a historic serial derecho moved into Wisconsin, triggering 10 confirmed tornadoes across the state.

On Dec. 15, 2021, an unusually strong low pressure system developed over the central Plains and traveled through the Upper Midwest and Great Lakes.

Thunderstorms quickly formed into a squall line and intensified further into a "serial derecho," which is a powerful squall line with multiple areas of intense wind and rotation. The line of storms traveled 60-80 mph from Kansas to Wisconsin.

The National Weather Service confirmed 10 tornadoes across Wisconsin and widespread wind damage occurred in many places.

Of the 10 tornadoes confirmed by the National Weather Service, there were 3 EF-0s, 3 EF-1s and 4 EF-2s. 

The town of Stanley, Wis. suffered the most tornado damage, with destroyed trees and outbuildings and several damaged homes. According to the National Weather Service, that tornado was the farthest north December tornado in U.S. history that was east of the Rocky Mountains.

Although December tornadoes are very rare in Wisconsin, Dec. 15, 2021 proved that they are still possible in the colder months and we should always be prepared.

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