National Weather Service United States Department of Commerce

A strong low pressure system will move through the area on Wednesday, bringing widespread showers and thunderstorms throughout the day. Some of these storms could be strong to severe, especially in the afternoon, especially in Illinois. Primary threats will be hail, damaging winds, and heavy rainfall with a few tornadoes possible.
Torrential rains are possible early Wednesday morning through Wednesday afternoon. There is a risk for flash flooding Wednesday, especially over far eastern Iowa and northern Illinois where soils remain wet from recent rainfall.
Severe storms are possible Wednesday. Here's a timeline on what you need to be doing to prepare for this potential dangerous weather day.