WINSTON-SALEM, N.C. - The severe winter weather that hit parts of the central and southern United States on Christmas Day moved eastward on Wednesday, causing flight delays and dangerous road conditions for holiday travelers in the Northeast and Ohio Valley.

Some flights headed for New York, Philadelphia and Newark, N.J., experienced delays averaging one to four hours due to the inclement weather, the Federal Aviation Administration said.

About 1,300 U.S. flights had been canceled on Wednesday, according to FlightAware.com. Several airlines waived ticket change fees for affected customers.

All four runways at Philadelphia International Airport were open on Wednesday, but that didn't prevent cancellation of physical therapist Mindy Bartscherer's flight to Minneapolis.

She and her son, Zachary Bartscherer, 24, a lobbyist from Washington D.C., had planned to visit family but instead waited forlornly in the baggage claim area for a ride back home.

They expected to return to the airport early on Thursday to try again.

"We were going to have dinner and see my 2-year-old niece," Mindy Bartscherer said of their thwarted plans for Wednesday night.

The National Weather Service issued blizzard and winter storm warnings in Illinois, Indiana and Ohio, as well as much of the Northeast, and cautioned that the wintry weather would create "treacherous" driving conditions.

More than six inches of snow might fall in those regions, while the area from western New York up into central Maine could get from 12 to 18 inches, the NWS said.

As of Wednesday morning, Bloomington, Indiana, already had nearly a foot of snow and Indianapolis had about seven inches, according to AccuWeather.com.

Severe thunderstorms and widespread rain were expected from southeast Virginia to Florida, the NWS said, and the eastern counties in North Carolina and South Carolina were under tornado watches or warnings for much of the day.

The wet and snowy conditions follow a major winter storm system that swept through the southern United States on Tuesday, spawning tornadoes in several states and causing the deaths of at least five people in weather-related road accidents.

Twisters struck in Alabama, Mississippi, Texas and Louisiana, flattening houses and causing injuries, according to the weather service. The storm also dumped record snowfalls in North Texas and Arkansas.

Nearly 200,000 homes and businesses remained without electricity in Arkansas and Alabama on Wednesday.

Damage assessments were conducted in the 11 Alabama counties that reported varying degrees of property destruction from Tuesday's storms.

The city of Mobile appeared to be hardest hit, with damage to as many as 100 structures.