National Weather Service United States Department of Commerce


An unseasonably warm and humid air mass fueled explosive thunderstorm development along a cold front during the late afternoon of April 7th. Thunderstorms initially developed over southern Wisconsin during the afternoon then slowly moved south into northern Illinois. The storms were prolific hail producers, with particularly large hail in the Rockford area as well as across some of the near northern Chicago suburbs. Numerous reports of hail 1" in diameter or larger were received with the most intense storms producing hail of 2 to 3 inches in diameter!


Additional information about the storms that hit eastern Iowa: 

Map of hail reports from 04/07/2020
Radar-estimated hail swaths and largest hail reports across Iowa, Wisconsin, and Illinois, during the evening hours of April 7, 2020. 
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Additional recaps can be found on the NWS Chicago Past Events Page
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