A winter storm unleashed snow and freezing rain on large swath of the southern United States on Saturday and threatened to bring treacherous conditions to the East Coast.

Approximately 25 million people in 13 states could be impacted by the snow and rain. Across the United States, nearly 800 flights were canceled and nearly 10,000 were delayed, according to flight tracking website Flight Aware.

A state of emergency was declared in North Carolina and Virginia as the winter storm, which was over parts of Texas, Oklahoma, Arkansas and Tennessee as of Saturday afternoon, continued to head east.

During a press conference, North Carolina Gov. Roy Cooper warned that the state anticipated the storm could cause up to half a million power outages.

"Tonight and tomorrow, it’s time to hunker down and stay safe ... this weekend is not the time to see a winter wonderland," Cooper said.

Along the southern side of the storm, flooding was a concern in warmer states, from southeastern Texas to parts of Georgia.

Approximately 14 million people were under winter weather advisories across the southern and eastern United states. Winter storm warnings were in effect along the northern side of the storm, including in parts of western North Carolina, southwestern Virginia, upstate South Carolina, eastern Tennessee, southern West Virginia, and northeastern Georgia, according to the National Weather Service.

The heaviest snowfall, which is expected to begin Saturday and continue until Monday, will affect northwest North Carolina and southern Virginia, according to the NWS

Prior to moving east, the storm had already dropped several inches of snow in southern states. In Lubbock, Texas, approximately 9.5 inches of snow had fallen as of 9 a.m. CST (10 a.m. ET) on Saturday, according to the NWS.

The Texas Department of Transportation warned travelers to drive with caution, and advised people to stay home if possible.

In other parts of Texas, flood watches were canceled following heavy rainfall from the storm.