An arctic air mass sprawling across the eastern, central and parts of the western U.S. on Monday will channel temperatures 20-30 degrees below already historically cold January averages and was poised to slam parts of the South with a disruptive winter storm.

Frigid temperatures engulfed the South on Monday ahead of a winter storm that's expected to spread heavy snow and disruptive ice around a region from Texas to north Florida that rarely sees such weather,