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.

A severe weather outbreak remains likely Monday afternoon and evening across parts of the Upper Midwest, including southern Minnesota and northern Iowa. Very large hail, damaging winds and strong tornadoes are expected,

One of the most active days of severe weather so far this season is ahead for the upper Midwest early this week, including a risk of strong, long-tracked tornadoes.