But today there is a change in the air. Very warm air and high instability in the atmosphere creates scattered storms across Chicago's west and southwest suburbs. Severe thunderstorms pile up across Will County. Torrential rains begin beating down. Funnel clouds poke out of storm clouds near Joliet, but none touch the ground.
High winds blow down branches and trees.
By late Wednesday almost four inches of rain falls over Joliet with even heavier concentrations over southern Kane and southern DuPage counties. Flooding is reported throughout the southwestern suburbs, primarily under viaducts, lower terrain streets and some basements. Round two begins early Thursday, after midnight. A line of strong storms with very heavy rain develops from Rockford to Aurora to Joliet to Gary, Ind. And that line refuses to budge. Hour upon hour of blinding rain floods roadways and basements quickly, since the ground has had hardly a chance to soak up Wednesday's violent storms.