A very dangerous few days are ahead for tens of millions of people across the South, Mississippi Valley and the Southeast.
Large hail, damaging winds and heavy rainfall are expected with the risk of flash flooding and destructive tornadoes.
"A significant tornado outbreak, with long-track, intense tornadoes is expected to begin this afternoon across parts of Louisiana and Arkansas, and then spread eastward and peak this evening into tonight across Mississippi and Alabama," the National Weather Service (NWS) warned Wednesday.
The current tornado threat in the South. (Fox News)
The NWS says the "widespread/substantial severe weather event is expected to continue into Thursday from southern Virginia southward into Florida, and westward into portions of eastern Kentucky/eastern Tennessee."
Residents are advised to have a way of being able to receive warnings, as a lot of these storms could come overnight.
The threat of severe weather in the Southeast through Thursday. (AP)
Alabama Gov. Kay Ivey has already issued a state of emergency as the "threat for potentially dangerous weather is rising for much of Alabama tomorrow," she wrote in a tweet.
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Meanwhile, accumulating snow will be the story across the central High Plains. Blizzard warnings are in effect for parts of Oklahoma, Texas, New Mexico and Colorado.
The national forecast for Wednesday, March 17. (Fox News)
Strong winds and heavy snow will make travel difficult, if not impossible.
Fox News' Greg Norman contributed to this report.
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