Chicago Forecast

Storm timing: What to expect and when as severe weather with hail, tornado chances loom

Strong to severe storms in Illinois could bring winds up to 75 miles per hour, large hail, heavy rain and even tornado chances

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Severe weather with threats of heavy downpours, wind gusts up to 75 miles per hour, large hail and the chance for a tornado was looming over the Chicago area Thursday, the NBC 5 Storm Team said.

According to NBC 5 Meteorologist Alicia Roman, strong storms had already begun developing along the Illinois-Wisconsin border Thursday morning with lightning, rumble of thunder and heavy downpours across Boone and McHenry counties.

By 7 a.m., rain had already begun to move into Lake County, Roman said, with non-severe showers and storms expected to last through 9 a.m.

LIVE RADAR: Track rain and storms across Chicago area, Illinois

At O'Hare and Midway International Airports, a ground stop had been issued "due to thunderstorms" through at least 8:15 a.m., the Federal Aviation Administration said.

According to the National Weather Service, the line of morning storms was also impacting parts of Kane, DuPage and Northern Cook Counties, with heavy downpours. Heavy lightning, wind gusts of 40 miles per hour and penny-sized hail were all possible, the NWS added.

By afternoon, clouds were expected to increase, Roman said, with more showers and storms developing around 1 p.m. and lasting through approximately 10 p.m.

Storms were expected to hit counties to the north between 2 and 3 p.m., traveling into Chicago and counties to the south and west by around 4 p.m., Roman said.

By 6 p.m., storms were expected to move into Northwest Indiana. Around 10 p.m., storms to the south and west were expected to gradually come to an end, Roman said.

According to the Storm Prediction Center, the entire Chicago area Thursday afternoon between 2 and 9 p.m. will be under a "slight" risk of severe weather, which ranks as level two of five. The storms carry the potential for several weather threats, Roman said, including damaging winds of up to 75 miles-per-hour, large hail up of to two inches in diameter, and heavy rain with localized flooding possible.

While the threat of a tornado remains low, it cannot be ruled out, Roman added.

"Be aware there is a tornado risk," Roman said. "It's not zero, but it's low."

Counties further west, including LaSalle County, will be at an even higher risk of severe weather, Roman said, with the Storm Prediction Center ranking those parts at an "enhanced" risk of severe storms, which ranks as level three of five.

Temperatures Thursday were expected to be hot and muggy, Roman said, with highs in the upper 80s to low 90s across all areas, including the lakefront, Roman said.

Dew points over 60 and 70 degrees Thursday afternoon could make things feel even warmer, Roman added.

"Feeling a little sticky out there," Roman said.

As the storms gradually move out overnight, temperatures will cool a bit. Roman said.

Temperatures Friday and Saturday will drop down into the low 80s, Roman said, with potentially cooler temperatures along the late. By Sunday, temperatures are expected to rise back into the 90s, Roman said.

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