LAKE COUNTY, Ill. — As a cold front pushed south, thunderstorms dumped over 4 inches of rain in portions of Lake and McHenry counties Wednesday night. A Flood Warning is in effect for those two counties until mid-afternoon with widespread road, small stream and viaduct flooding reported. With heavy runoff, eventual flooding on portions of the Des Plaines and Fox Rivers is also anticipated. Early reports indicated 4.35 inches in Long Lake and 4.04-inches at Buffalo Grove, with many other reports in the 2- to 3-inch range.
The frontal boundary well south of Interstate 80 Thursday morning is forecast to move back north as a warm front this afternoon and aided by peak heating is expected to trigger another round of showers and thunderstorms, some possibly severe. A strong cold front will approach and move through from the west overnight preceded by a band of strong t-storms. Clearing skies and cooler temperatures are expected Friday.
The Chicago area may be impacted by a Slight Risk (yellow-shaded area on the map below) and Marginal Risk (green-shaded area) of severe storms forecast the next 24 hours by the National Storm Prediction Center. The National Weather Prediction Center has much of the Chicago area in a Slight Risk for excessive flood-producing rains in the next 24 hours (map below).
Risk of severe thunderstorms Thursday/Thursday night...
Excessive Rainfall Outlook Thursday/Thursday night...
Some of the early heavier Chicago area rainfall reports...