Severe thunderstorms, including two probable tornadoes, ripped through the Chicago area on Sunday, May 17, 2020, causing major flooding and leading to numerous water rescues.
With almost 76 mm (3 inches) of rain on Sunday night alone, Chicago is now heading toward its wettest May on record. 208.3 mm (8.2 inches) of rain fell on the city so far this month -- of which 200.1 mm (7.88 inches) from March 14 - 17. This 4-day stretch of heavy rain would have been enough to break the entire monthly record prior to 2018.
There have only been 33 months in Chicago dating back to 1871 that have had more precipitation during the entire month than what fell in just those 4 days.
May 14 through 17, 2020 is now the 4th wettest 4-day stretch in Chicago's recorded weather history. The first place is held by August 13 - 16, 1987 with 326.1 mm (12.84 inches), 2nd July 21 - 24, 2011 with 218.7 mm (8.61 inches), and 3rd September 11 - 14, 2008 with 214.6 mm (8.45 inches).
Chicago's wettest May on record was recorded in 2019 when 209.5 mm (8.25 inches) fell; 2nd wettest is still May 2018 with 208.5 mm (8.21 inches).
To understand this obvious increase in heavy rainfall registered since 2018, note that for the 4th wettest May on record you have to go back all the way to 1945 and to 1883 for the 5th (May 2020 is currently Chicago's 3rd wettest May).
"The water is only going to continue to rise even after the rain stops because the ground is so heavily saturated-- the water has nowhere to go," said meteorologist Matt Friedlein.
The Chicago River became swollen, flooding the Riverwalk in some spots. Meteorologists forecast the water levels to keep rising. There was also a rapid-rise state Sunday evening.
In response to the inundation, the Metropolitan Water Reclamation District said they had reversed the flow of the river to Lake Michigan, at both the Wilmette Pumping Station and Chicago River Controlling Works.
Significant flooding was reported on roadways across the Chicago area, including Lower Wacker Drive, where the water level had increased to the point that the Chicago Fire Department had to deploy boats to rescue trapped people and motorists. At least six people were removed from the underground street.
Lower Wacker drive. Entire lower level flooded. All traffic suspended. pic.twitter.com/O3t6Kv6WwD— Chicago Fire Media (@CFDMedia) May 18, 2020
Major flooding occurring on Joliet’s far west side and Plainfield around Caton Farm and County Line Roads this evening. Video taken by JWC forecaster Brian Delach. #ilwx @NWSChicago pic.twitter.com/vCG2nFluX9— Joliet Weather Center (@JolietWeather) May 17, 2020
Lower Wacker drive closed due to flooding. Water still rising. CFD has removed homeless who were camped out pic.twitter.com/xhk5EqgimD— Chicago Fire Media (@CFDMedia) May 18, 2020
So far 6 people rescued . Human services notified. pic.twitter.com/qVgM6H4gph— Chicago Fire Media (@CFDMedia) May 18, 2020
The Cook County Department of Transportation warned that about 152.4 mm (6 inches) of water could stall many vehicles, while about 0.3 m (1 foot) of water may cause some vehicles to float, and 0.6 (2 feet) of water will wash away most vehicles.
Meanwhile, weather spotters reported one possible tornado striking first the area south of Sandwich in far northeast LaSalle County, and hitting the area near Braidwood along the Grundy County next. Forecasters said there were no major damages. Another tornado briefly touched down in central Illinois which had moved through the Macon area, damaging several trees.
Heavy rains are expected to continue until Tuesday, May 19.
Featured image credit: Chicago Fire Media