The National Weather Service issued a Flash Flood Watch Wednesday that remains in effect until 11 a.m. for Cook County and surrounding counties in Illinois and Indiana.
Another half inch of rain is expected to fall this morning, bringing the total rainfall in the last 24 hours between one and two inches, the weather service said. Poor drainage along rivers, streams, creeks and retention ponds may lead to lowland flooding.
The alert applies to Cook, DeKalb, DuPage, Ford, Grundy, Iroquois, Kane, Kankakee, Kendall, La Salle, Livingston and Will Counties in Illinois and Benton, Jasper, Lake, Newton and Porter Counties in Indiana, the weather service said.
A flood advisory is also in effect for the Des Plaines River at Riverside, or from Roosevelt Road in Forest Park downstream to Hodgkins, until late Thursday night, the weather service said. Sections of the river in Gurnee, Lincolnshire and River Forest may also flood.
In Chicago, the north branch of the Chicago River at Pulaski Road, or from Central Avenue down to its meeting with the North Shore Channel, is also under a flood advisory until late tonight, according to the weather service. A section of the Des Plaines River in Irving Park on the Northwest Side may also see some flooding.
Showers and thunderstorms will continue throughout the day before finally slowing down towards the evening, the weather service said. Temperatures are expected to reach the mid-60s during the day and fall to a low of 45 degrees at night.
The rain will pick up again Thursday with likely showers and a possible thunderstorm, while daytime temperatures hover around the mid-50s.
By Friday, the National Weather Service expects mostly sunny skies with temperatures in the low 50s.