Forecasters are warning millions of people in the central U.S. to watch for bad weather this week as colliding air masses threaten to generate high winds and possibly tornadoes. The threat reaches across America and the Stateline is included. Here's more.

The threat Wednesday stretches from San Antonio to Chicago to Cincinnati.

Missouri, southern Illinois and northern Arkansas face the greatest severe weather threat.

According to NBC Chicago, The Storm Prediction Center said "Monday that the storms' severity would be dictated by how much warm, humid air can funnel into the area before a cold front approaches from the west".

Jon Durr, Getty Images

The National Weather Service warned that storms with heavy rain and strong winds are expected in the Chicago area Wednesday night, with some thunderstorms becoming strong to severe.

Wind gusts of up to 50 mph are also expected in the Stateline Thursday ahead of a big temperature swing. Enjoy the high 50's this week because we will be in the 40's for the weekend and maybe even a chance of flurries Friday.

Basically, strap yourself in for a roller coaster ride this week.