The main corridor of severe thunderstorms through Thursday night will line up roughly from the Ohio Valley to the lower-Mississippi Valley, Tennessee Valley and the Deep South. Damaging straight-line winds are the main threat; however, a few tornadoes are also possible.
Friday will bring the potential for scattered severe thunderstorms with localized damaging winds and perhaps an isolated tornado to the East Coast anywhere from the eastern Pennsylvania to northern Florida. The cold front responsible for the storms will then push off the East Coast Friday night, allowing the weekend ahead to be mostly free of severe weather.
In addition to the severe thunderstorms, heavy rain has caused significant flooding in the Midwest. The Chicago metro area was hit hard by major flash flooding on Thursday morning.
Major flooding is forecast for several river gauge locations along the Mississippi River in Iowa, Illinois and Missouri. Several river gauge locations in northern Illinois, southern Wisconsin and Lower Michigan are also forecast to see major flooding.
Altogether, 17 river/stream gauge locations were in major flooding as of early Thursday afternoon. That number is predicted to rise to 75 by early Friday afternoon in parts of Missouri, Iowa, Illinois, Wisconsin and Michigan.