Intense rains fell Sunday morning at a rate rarely seen in Chicago, overwhelming the city’s stormwater system and flooding streets, viaducts and basements.
Though official gauges at O’Hare and Midway airports notched less than 2 inches of rain, reports from private weather stations told a different story: 5.63 inches in Albany Park, 5.86 inches in Portage Park and 5.9 inches in Lincoln Square.
The northern edge of the storm system essentially parked itself over the North Side and kept raining on the same area, said Todd Kluber, a meteorologist with the National Weather Service.
If the deluge had kept up for a solid hour, the rate would have been in the 6-to-7-inch range, Kluber said. That’s heavier than the 4-to-5 inches per hour severe thunderstorms are capable of dumping.
“We can handle 3 inches, but the rate at which the rain fell, we don’t see rainfall rates that high,” he said. “There’s just nowhere for that water to go.”
Although the Department of Water Management, which maintains the city’s sewer system, has replaced and lined 717 miles of it over the last decade, “unprecedented rainfall events” like Sunday’s “require time for the sewer system to process,” department spokeswoman Megan Vidis told WTTW News.
Water temporarily pooling in streets is by design, with inlet control valves installed on some catch basins to modulate the flow of stormwater into the sewers.
The downpour led to some dramatic images of stranded motorists and geysers bursting through manhole covers. The spouts are a rare effect which occurs when too much water rushes into a dropshaft and traps air that’s normally vented.
— The Architect (@TheArch01196450) September 11, 2022
Same spot. Pulled off the SnapMap, unknown user pic.twitter.com/lyOpEkX0Qz
— WindyCity Weather and News (@WindyCityWxMan) September 11, 2022
The city’s 311 system was inundated with calls from people reporting water in their basements or streets, and pointed people to log their complaints online at http://311.Chicago.gov or via the CHI311 mobile app.
Some of the hardest hit neighborhoods Sunday were those that had previously experienced “100-year” floods caused by the Chicago River overflowing its banks. A $70 million tunnel has since alleviated concerns related to the river (which remains well below flood stage), but the weekend’s rains were a reminder that Chicago’s infrastructure remains vulnerable to extreme weather events.
More rain is in the forecast for Monday, but then drier conditions are expected through the rest of the week.
Area of moderate rain west of I-39 will move east this morning and early afternoon, leaving behind isolated showers this afternoon into tonight. Fall-like temperatures Tuesday will give way to above seasonal temperatures later this week with mostly clear skies. #ilwx #inwx pic.twitter.com/Nhht67QcjF
— NWS Chicago (@NWSChicago) September 12, 2022
Did you see flooding during the Sunday storm? Send us your photos at [email protected] and we may feature them online or on "Chicago Tonight."