Millions hunker down as storm hits eastern US

Millions of Americans hunkered down Sunday as a major winter storm hit the eastern United States with heavy snow and ice, knocking power out to an estimated 235,000 people and counting.

The National Weather Service (NWS) said the storm was bringing a miserable combination of heavy snows, freezing rain and high winds, impacting the southeast and coastal mid-Atlantic before moving up to New England and southern Canada.

Traffic has already been seriously disrupted, with thousands of flights cancelled and a portion of busy interstate highway I-95 closed in North Carolina. 

Drivers were warned of hazardous road conditions and major travel headaches from Arkansas in the South all the way up to the northeastern state of Maine.

"Arctic air already in place across the central and eastern US will work in concert with this dynamic system to deliver a wide swath of more than a foot (30 centimetres) of heavy snow northward across the upper Ohio Valley through the lower Great Lakes," the NWS said.

The storm spawned damaging tornadoes in Florida and flooding in parts of the coast, while in the Carolinas and up through the Appalachians, icy conditions and blustery winds raised concerns. 

In all, more than 80 million people fell under the winter weather alerts, US media reported.

Some 2,900 flights within, into or out of the US were cancelled by mid-afternoon Sunday, according to the FlightAware website, and a further 2,400 were delayed.

About 235,000 customers had already lost power in the southeast, including more than 150,000 in the Carolinas.