A wide swath of the Midwest and Plains states is under a tornado watch and severe weather conditions are forecast to persist into next week, the National Weather service said Thursday.

Cities such as Chicago, Minneapolis and Milwaukee are at risk for a severe weather outbreak, forecasters said.

A strong storm system coming out of the Great Plains brought severe thunderstorms to the Midwest on Thursday, including a reported tornado that swept through a small Wisconsin city, damaging businesses and homes, forcing road closures and downing power lines, the authorities said.