Damaging winds, hail, isolated tornadoes, and torrential rain are possible with a string of storms approaching Chicagoland today.

Rain came down fast and hard Wednesday night in Chicago, creating some hazardous situations not only for drivers, but for first responders who were busy rescuing people who were stuck in high waters.

Another night of potentially dangerous storms is possible in the Chicago area Friday as the threat for severe weather increases heading into the afternoon and evening hours for northern Illinois.

More than a month's worth of rain fell on Chicago in 90 minutes on Tuesday evening, according to the National Weather Service (NWS). "There were numerous reports of flooded viaducts, several reports of water rescues, and a few reports of flooded basements," the NWS said.

Chicago flash flooding caused sudden road washouts, and water rescues had to be made at more than one location on the West Side.

The flood watch is in effect until 7 a.m. Friday for Cook County, the collar counties and the majority of northern Illinois, according to the National Weather Service.

Texas. North Carolina. Illinois. New Mexico. Flash flooding has surged into the spotlight in the last week with record-breaking flood events occurring nearly back-to-back across the country. Here’s why they happened now and why floods are becoming more intense.

Straighter, smoother streams flow more violently than those that meander due to a reduction in friction. Areas with steeper terrain can see water accelerate downhill at a much faster rate causing a more destructive flash flood than flatter, open areas.