The severe weather sweeping across the Midwest has forced the cancelation of about 735 flights at Chicago's O'Hare International Airport and flight delays of 90 minutes.
The Chicago Department of Aviation on Thursday is also reporting 30 cancelations at Midway International Airport and delays of up to 45 minutes.
The National Weather Service is forecasting hail, damaging winds and possibly tornadoes as a strong storm front moved across the Plains.
The weather service's "enhanced risk" area stretched from northeast Texas to Michigan, Wisconsin and across the upper Midwest.
Tornado watches were posted Thursday for northern Illinois, including Chicago, and areas of Iowa, Missouri and Wisconsin.
A tornado was reported near Peoria, Illinois on Thursday afternoon, but there were no immediate reports of damage.
