Updated 06/18/14 – 11:03 a.m.

CHICAGO (CBS) — Keep an umbrella handy on Thursday.

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Thunderstorms began moving through north and northwest suburbs late Wednesday morning, bringing wind gusts of up to 45 mph, frequent lightning strikes, and occasional heavy downpours. The same system was expected to blow through the city later Wednesday morning or early Wednesday afternoon.

Most of the lightning was concentrated over the lake, but there was also plenty of lightning activity stretching from throughout the narrow band of storms as they head east.

With rain and storms possible for the next few days, the National Weather Service has issued a flood warning for Lake County from Friday morning through Monday afternoon. Forecasters said the Des Plaines River could reach flood stage on Friday near the town of Russell. As of 7:45 a.m. Wednesday, the river there was at 6.6 feet, less than half a foot shy of flood stage. The National Weather Service said the river could rise to 7.1 feet near Russell by Friday evening, and flow into surrounding farms and marshland.
The risk of severe weather was vast on Wednesday, extending from the Canadian border in North Dakota and Minnesota to the Mexican border in Texas, and east across the Great Lakes all the way to the New York coast.

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Approximately 65 million Americans were at risk of severe weather on Wednesday.

In the Chicago area, there is a general risk of severe damaging winds and large hail. Isolated tornados were not out of the realm of possibility.

The high temperature was expected to reach about 89 degrees in Chicago on Wednesday, and the storms should drop the temperature down to about 69 overnight.

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Thursday brings another day of warm, humid conditions and possible storms, a pattern likely to repeat through Sunday.