Millions of Americans across the country are on alert for a severe weather outbreak as violent, long-track tornadoes with damaging winds of up to 80 mph and large hail are expected across the Midwest and South with the cross-country storm moving east.

About 47 million people faced an enhanced to moderate severe storm threat from Madison, Wisconsin, to Birmingham, Alabama.

Weather forecasters warn about a major multiple-day outbreak of severe weather that includes multiple strong tornadoes from the Mississippi Valley to the Gulf Coast, Great Lakes and Atlantic coast through the weekend.