Millions in the Upper Midwest face the possibility of a severe thunderstorm outbreak Monday—the start of several days of extreme weather threats across the country this week.

Monday is probably the peak, but a storm risk shifts eastward Tuesday. Cities in the highest risk for tornadoes include Minneapolis and Rochester in Minnesota.

Monday, April 28 is looking like a severe weather day in the region. Tornadoes, large hail and damaging winds are all possible, including a threat of "strong tornadoes."