Millions of people across the northern Gulf Coast braced Tuesday for a rare winter storm that's expected to scatter heavy snow, sleet and freezing rain around the Deep South as a blast of Arctic air plunges much of the eastern U.

Around 40 million people in the U.S. are under a winter storm warning from an unusual blast of severe winter weather.

Most of the United States is being assailed with extreme winter weather this week as Arctic air blasts south from Canada, snow tracks up the Northeast coast and a potentially crippling winter storm takes aim at the South.