Where a severe storm outbreak could spawn tornadoes, large hail and damaging winds tonight

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.

​ 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. Read More Breaking News, Latest News and Videos | CNN