A cold front interacting with warm, moist air is forecast to bring storms to much of Mississippi later this week.

Storms with lightning and hail and at least one observed tornado were moving through the upper Midwest Monday with the potential for strong tornadoes. The National Weather Service said the highest risks — a 4 on a scale of 1 to 5 — were in portions of southern Minnesota,

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.