Forecasters say a warm front is expected to stall over southern Wisconsin through Sunday, possibly producing heavy rainfall along the front through the weekend.
And this comes after 30 of the state's 72 counties were declared federal disaster areas because of last month's flooding and other weather problems.
The tornado was seen by two citizens as it touched down at 3:38 p.m. and stayed on the ground for about a mile and a half in the rural area around Sheboygan and Sheboygan Falls.
At about the same time, a wind gust estimated at 70 mph was reported at Sheboygan by a trained weather spotter.
In Milwaukee, a wind gust of 60 mph was recorded at Timmerman airfield on the northwest side of the city.
Gusts of similar strength were reported in Waukesha, Washington and Fond du Lac counties as the storms moved through.
In Sauk County north of Madison, heavy rain caused flash flooding at Reedsburg, where sandbagging was in progress.