Severe thunderstorms Sunday night could renew flooding potential across northern Illinois

A severe storm watch was issued Sunday evening for scattered to numerous showers moving through northern Illinois and to the east. Chicago will experience the most downpours between 7 and 11 p.m. as the system exits the area by 3 a.m.

“This round of storms could end up being severe and bring a renewed potential for flooding,” after overnight storms caused damage in the suburbs, said Rafal Ogorek, a meteorologist for the National Weather Service office in Chicago.

Because all the storms will produce lightning strikes, meteorologists urged people to seek shelter indoors when they hear thunder. The strongest storms may produce tornadoes, strong winds that knock down tree limbs and fences, damaging hail capable of denting cars and torrential rains that can flood roads and other areas where it rained significantly Saturday night, including most of the Rockford metropolitan area and parts of the Chicago area.

More thunderstorms are possible Monday beginning at 3 p.m. and through the night until early Tuesday. The humidity in the air will likely combine with 90-degree temperatures to produce dangerously high heat indices — which are a measure of how heat feels to the human body — in a range of 100 to 110 degrees in and around Chicago.

Heat waves are hotter and cooling costs are rising in cities such as Chicago, studies show

Storms could cool down temperatures Monday, but uncertainties remain: If the rain holds off until the midafternoon, the weather service might have to issue heat advisories. A cold front will bring additional storms Tuesday, after which conditions will be cooler and drier by midweek.

Authorities suggest that urban residents remove valuables from low-laying and flood-prone areas such as basements and outdoor locations with poor drainage, prepare to change travel routes if driving and know where to find higher ground.

Just after 8:30 a.m. Sunday, a severe thunderstorm caused destruction in downtown Joliet.

The Illinois Rock & Roll Museum on Route 66 endured significant damage. However, all artifacts in the nonprofit honoring Illinois’ music history are safe. A guitar statue mounted on the facade also appears fine, according to museum founder and executive director Ron Romero.

“Though this is a tremendous amount of damage, I am confident (we) will be able to rebuild,” he wrote in a Facebook post Sunday morning.

The damage was caused by a strong downward wind system in the thunderstorm, Ogorek said. Nearby, 60 mph winds were reported around the time of the incident.

The roof of the Joliet Junior College City Center Campus around the block appeared to have been ripped off by the wind, and debris hit the museum, according to Romero and Roy Wickiser, a bystander who was working at a music venue across the street from the museum.

The museum was hit by a 30-foot wide, 60-foot long and 4-foot deep HVAC cover that flew off the roof of Joliet Junior College’s City Center Campus, according to college spokesperson Kelly Rohder-Tonelli. Classes at the City Center Campus will be virtual on Monday and Tuesday due to the storm damage.

“I was relieved because just prior to this happening, there were cars that were driving right where (the roof) landed. Had they just been two or three minutes later, they would have been absolutely demolished,” Wickiser said.

No injuries have been reported. Joliet police were using drones to investigate the area.

This morning’s rain made Sunday afternoon hot and muggy, with a high of 93 degrees forecast and a heat index near 100 degrees in the Chicago area.

Editor’s note: Earlier versions of this story misstated which building sustained roof damage. The building is Joliet Junior College.