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.

A winter storm warning was issued by the National Weather Service on Monday at 3:53 a.m. valid from Tuesday 6 a.m. until Wednesday 6 a.m. for Choctaw, Washington, Clarke, Wilcox, Monroe, Conecuh, Butler,