Snow, freezing rain and rain are underway in the southern Plains as a potent winter storm strengthens Thursday.

A powerful winter storm brought heavy snow and icy conditions to parts of the U.S. South on Thursday, forcing officials to close schools, cancel flights and warn residents in some of the worst-hit areas to stay off roads as it lumbered eastward through Oklahoma and Texas.

Another blast of winter storms is closing schools, snarling flights and putting millions of residents on alert across parts of the Deep South and south-central U.S. The storm started dumping a mix of sleet and heavy snow Thursday in north Texas and Oklahoma,