EF2 tornado in Chippewa County, Wisconsin

This tornado first caused damage to groves of trees southwest of Stanley, then affected a couple farmsteads. It intensified significantly as it approached Stanley, demolishing an outbuilding and then two outbuildings with a construction business. An historic train depot had a portion of its roof removed. A high tension power line was blown down. About six homes had their roofs removed, and in the northeast edge of Stanley, a roof and outer walls were removed from a portion of a house. The tornado continued into northwestern Clark County where it damaged more trees and outbuildings (see entry from NWS La Crosse).

A low pressure system of historic strength led to a variety of high-end weather impacts from the central plains to the Upper Midwest and Great Lakes December 15-16. An unprecedented December severe weather unfolded over portions of Minnesota and Wisconsin Wednesday evening, with the Storm Prediction Center issuing their farthest-north Moderate Risk for the Month of December. A serial derecho moving at 60-70 mph tracked from Kansas to Wisconsin, resulting in over 400 reports of damaging wind and numerous tornadoes. Most of the damage across our area occurred from south-central Minnesota through west-central Wisconsin. The strongest tornado in west central Wisconsin hit Stanley.

Before the thunderstorms, strong southerly winds led to record high temperature at many sites across the Upper Midwest. Temperatures warmed into the mid to upper 50s across much of central Minnesota and western Wisconsin, and even exceeded 60 degrees across southern Minnesota. The warm temperatures melted what was left of the snowpack from the December 10 winter storm, which led to widespread dense fog through much of the morning and afternoon.

After the thunderstorms, strong gradient winds and widespread wind gusts in excess of 50 mph developed for several hours late Wednesday night and into the overnight hours. The Redwood Falls airport measured a gust of 78 mph at 11:30 PM.

Temperatures quickly fell below freezing across western and central Minnesota Wednesday night, causing rain to change over to a wintry mix of freezing drizzle and snow. Snowfall accumulations of 1-4 inches, along with the strong gusty winds, led to low visibility and travel hazards late Wednesday night into Thursday morning.