According to the National Weather Service Central Illinois Facebook page, widely scattered strong to severe thunderstorms will develop across central Illinois late this afternoon into the early evening.
Given unseasonably high amounts of instability and wind shear in the environment, the thunderstorm cells will be capable of producing damaging wind gusts in excess of 60 mph, large hail greater than quarter-sized, and a few tornadoes.
Further west…a solid line of thunderstorms is expected to develop along a cold front across Iowa and Missouri early this evening. This line of storms will surge eastward into central Illinois tonight.
At this time, it appears the greatest risk for widespread severe weather will develop across the Illinois River Valley between 6pm and midnight…along the I-55 corridor between 9pm and 3am…and further east to the Indiana border between 3am and 6am.