Twenty states, from Texas to Delaware, were on alert Friday for snow and ice as the storm continued to move across the South.

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.

Winter storms closed schools, snarled flights and put millions of residents on alert across parts of the Deep South and south-central United States.