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.

For example, Lake Charles, La., along the Gulf Coast, showed snowfall rates of over 1 inch per hour this morning and early afternoon and visibility down to a quarter of a mile with blowing snow. This is one of the reasons why blizzard warnings were posted briefly for that region earlier.

The South is bracing for a major winter storm, most of the nation remains gripped by extreme cold, and high winds could fan flames in California.

Roughly 40 million people from Texas to the Carolinas are under winter weather alerts, as a rare winter storm brings bone-chilling temperatures and potentially historic snowfall to cities unused to harsh cold weather.

A winter storm sweeping through the U.S. South on Tuesday was dumping snow at levels millions of residents haven't seen before. Moisture from the Gulf of Mexico was combining with a low-pressure system and chilly air to drop significant amounts of snow in some spots.