A major winter storm will bring snow and ice to the southern U.S. this week, followed by a cold blast. AccuWeather's Jon Porter warns of dangerous travel conditions for the region.

Snow will turn into sleet and freezing rain along parts of the Southeast, as well as southern Arkansas, the weather service reported. Forecasters warn that icy conditions, between a tenth and a quarter inch of ice, will make travel dangerous for many. Power outages and downed branches are also a concern.

The storm caused thousands of flights and dozens of train trips to be delayed or canceled. At Ronald Reagan National Airport in Washington, all runways were closed Monday evening.