Tornado and severe storm warnings in effect across Chicago and northwest Indiana, weather officials say

Weather officials warned storms that were roiling across the Chicago region Monday afternoon could intensify again after 4 p.m. as the severe weather moved toward the south suburbs and Northwest Indiana.

Officials were keeping an eye on stronger thunderstorms developing over Wisconsin that could move towards the Chicago area later in the afternoon, according to Kevin Donofrio, a meteorologist with the weather service in Chicago. However, there was still a lot of uncertainty in the forecast, Donofrio said.

As far as the first batch of storms, weather so far has left “a smattering across the area here of large hail and damaging winds,” Donofrio said. Just after noon, Midway International Airport saw a gust of 70 mph, per Donofrio.

Earlier Monday, officials issued tornado warnings in Cook, DuPage and Will counties in Illinois and Porter and Lake counties in northwestern Indiana. Officials also issued severe thunderstorm, hazardous heat and flash flood warnings across the Chicago area.

More than 200,000 homes were without power as of 1:40 p.m. Monday, according to ComEd.

Winds up to 70 miles per hour and ping pong ball-sized hail are possible in the region in the early afternoon.

“We already have ongoing storms,” National Weather Service meteorologist Kevin Doom said. “We have some reports already of quarter -sized hail or even slightly larger. Some of these storms are continuing to grow here.”

Stifling humidity will combine with warm temperatures to produce heat indices between 100 and 115 degrees. The highest heat indices are expected near the I-39 corridor. Monday’s high is 91.

Rolling thunderstorms grounded flights at O’Hare International Airport and Midway Airport Monday afternoon, with flight delays averaging 2 hours according to the Federal Aviation Administration Air Traffic Control System Command Center.

Service on the CTA’s Purple and Yellow Lines had been temporarily suspended as of early afternoon Monday due to debris on the train tracks, according to alerts posted on the agency’s website. The Red Line was operating with major delays.

Across the region, residents reported fallen trees that smashed parked cars and broke street lamps. Weather officials warned those outside to be careful of flying debris and to seek shelter immediately. Residents indoors were urged to move to basements or interior rooms on the lowest floor of the building, and to avoid windows.

Relief will be in sight, though, weather officials said. Monday is forecast to be the last day of extreme heat and humidity, with a cold front moving through Monday evening, and dry conditions expected through Thursday, Doom said.

Midday conditions at Chicago O’Hare Airport were overcast at 85 degrees. Further south at Midway Airport, conditions were overcast at 88 degrees.

• Chicago Tribune reporter Talia Soglin contributed.