After heavy rains flooded viaducts, stranded cars, and sent water surging into basements on Sunday, the National Weather Service issued a flash flood warning for a portion of northeastern Illinois, including Chicago’s northern metro area.
Images of cars partially submerged under underpasses and plumes of water shooting up from sidewalks were widely shared on social media by Chicago residents.
The Chicago Bears posted videos of the team warming up on a soaked field in the pouring rain, suggesting that they had no plans to postpone their scheduled football game against the San Francisco 49ers at noon local time (1700 GMT).
However, the rain continued to fall lightly until around 11 a.m. CT, the NWS issued a warning that floodwaters would not go down for some time.
In a Twitter post, the city urged residents not to drive through floodwaters on streets, viaducts, and low-lying areas.
Extreme flooding is expected to worsen in the Midwest, according to the Intergovernmental Panel on Climate Change (IPCC) report (available at https://report.ipcc.ch/ar6wg3/pdf/IPCC AR6 WGIII FinalDraft FullReport.pdf).
According to Chicago’s water management office, the frequency of extreme rainfall events that are “very local, very intense, and hard to predict” has increased in recent years.
Rainfall rates of 2 inches (5 cm) per hour or more can cause localized flooding by saturating sewage systems, mains, and even residents’ private drains, which can then force water into their basements. Therefore, the city has started putting in water blockers on catch basins, which helps keep the sewers from overflowing but can make street flooding worse.