Powerful thunderstorms are set to threaten the Northern Plains and Midwest this weekend, tracking from Sioux Falls to Cincinnati. Damaging winds, large hail and isolated tornadoes are possible. Heavy rainfall could lead to major flooding concerns as storms push through the region. Chicago and Madison are the larger populations in the crosshairs this weekend, with conditions expected to rapidly change. With state fairs underway in Indiana and Wisconsin, stay weather aware and know the latest forecast before heading out. Here's what you need to know.