Thunderstorms, some more than 10 miles high, erupted with a vengeance Monday afternoon in the muggy, energy-charged atmosphere dripping with nearly 1.75” of evaporated moisture. The powerful winds which gushed from the storms reached 57 mph at Kenosha, 60 m.p.h. south of Algonquin and 50 m.p.h. at Romeoville. Sections of McHenry County were walloped by 3” of rain. But, nowhere were the storms’ effects more severe than in DeKalb, hit first by temperature-crashing 50+ m.p.h. gusts, 3/4-inch diameter hail and then a blinding cloudburst which deposited as much as 4.25” of rain—more than typically occurs over a full July—in just 80 minutes time. The deluge closed roads, forced evacuation of one Northern Illinois University dorm, left cars stranded and basements flooded. At their height, the storms unleashed more than 2,400 cloud- to-ground lightning strokes in a single 10-minute period within a 240 miles radius of Chicago.
--By Tom Skilling, WGN-TV Chief Meteorologist
