Event narrative (NOAA)
Thunderstorms produced torrential rainfall across northern Cook County with rainfall rates between 2 and 4 inches per hour which caused widespread flash flooding. Chicago O'Hare Airport measured 6.78 inches of rain during a 3 hour period between 1251 am CDT and 351 am CDT, with 3.19 inches falling between 151 am CDT and 251 am CDT. This extreme rainfall which fell across much of northern Cook County caused widespread street, parking lot and basement flooding with numerous cars stranded and submerged. Retention ponds, creeks and small streams quickly overflowed their banks.||In Prospect Heights, a sewage lift station lost power for about 6 hours, causing the flooding to be worse in some areas. Some basements were completely flooded with flood water and sewage 8 to 10 feet deep. In Mt.
Other notable flash flood events in Illinois
Source: NOAA/NCEI Storm Events Database. Deaths and injuries are those NOAA classifies as direct. Damage is the reporting office's estimate at the time and is not inflation-adjusted. This is a catalogue record, not a forecast.