The tornado watch is in effect till 7 p.m. for Chicago, the surrounding south and west suburbs and northwest Indiana. The National Weather Service warns of tornadoes, hail the size of ping-pong balls and 70 mph winds.

A tornado watch for much of the Chicago area has been issued as possibly severe storms approach the region, potentially bringing damaging winds and hail as well.

Dramatic temperature swings and more rounds of serious storms are expected to roil Chicago much of the week, according to the National Weather Service.