Snow, sleet and freezing rain predicted to fall throughout the day Thursday could spell delays at Dallas airports.

The Tennessee Valley could see some of the heaviest snowfall, with 6 inches expected on Friday. A wide swath of the country is under winter weather warnings and advisories and will see impacts including "widespread closures, treacherous travel, scattered power outages, and downed branches," the weather service said.

A winter storm that brought snow to Dallas and threatens the US South with ice and sleet has grounded more than 1,000 flights and is raising the risk of power outages through the region.