Chicago experienced one of its heaviest rainfall events since September 2023 on Tuesday night, leading to water rescues and flooded basements.An outflow boundary surging northward into the city from earlier storms south of Interstate 80 led to one lone thunderstorm cell developing over Chicago just before 9 p.

In parts of Chicago, flash flood alerts rang Tuesday, warning of dangerous conditions as cars were stranded and submerged on highways and water rescues were conducted, but how much rain actually fell across the region and how fast did it all happen?