Forecasters on Tuesday warned residents of much of the Upper Midwest to brace for possibly severe afternoon weather as a cluster of powerful thunderstorms swept east and south out of Minnesota and Iowa.

The National Weather Service issued severe weather outlooks for parts of Michigan, Indiana, Wisconsin and Illinois, including Chicago, and warned the dangers could include the possibility of isolated tornadoes in some areas.

There's more than one system, but they're very tightly packed, said Rich Thompson, lead forecaster at the National Storm Prediction Center in Norman, Oklahoma.

There are some pretty strong storms out there.

In Wisconsin, where a twister touched down west of Green Bay late last week, killing one man and causing major damage, forecasters said strong storms were expected to bring torrential rainfall and moderately severe hail from Rhinelander south to Marinette.

The impending storm forced the Green Bay Packers football team to move its practice indoors.

Forecasters at the NWS said thunderstorms expected to sweep through the Chicago area this afternoon and evening could produce damaging winds in excess of 60 miles per hour, quarter-sized hail, drenching rains and frequent cloud to ground lightning.