Published: Dec 25, 2010 5:45 PM EST
Updated: Dec 25, 2010 2:45 PM EST

NASHVILLE, Tenn. (AP) - With a rare white Christmas in parts of the Southeast and snow predicted for the nation's Capital, airlines canceled hundreds of flights and urged travelers to rethink their plans, while travel authorities warned of potentially dangerous roads.

After blanketing sections of the Midwest and hampering motorists there on Christmas Eve, the storm dipped south late Friday. Winter weather advisories were in effect Saturday morning from Arkansas to the Carolinas and from West Virginia to central Alabama. Much of North Carolina was under a winter storm warning.

The National Weather Service said the storm could bring more than 5 inches of snow to the Washington region. Meteorologist Stephen Konarik said the storm could hit the area Sunday morning and end Sunday night or early Monday, with the peak snowfall Sunday afternoon and early evening.

The wintry weather is the result of a low pressure system moving along the Gulf coast. It is expected to intensify and move northeast on Sunday to the mid-Atlantic states and New England.

The weather service was forecasting possible snow for the New York and Boston areas, starting Sunday and continuing into Sunday night, with overnight temperatures in the 20s and wind gusts up to 30 mph.

Delta Air Lines spokesman Kent Landers said 500 weather-related flight cancellations were planned for Saturday nationwide. That included 300 of the 800 scheduled departures from the Atlanta hub.

The airline was monitoring the storm's path, Landers said, and would decide on possible additional Sunday cancellations as the time approaches. Landers said the airline is encouraging customers to consider changing flight plans as a result of the snow. Anyone with travel plans through Boston, New York, Baltimore, Washington and Newark, N.J., on Sunday or Monday can change their flight without a penalty as long as they travel by Dec. 29.

AirTran spokeswoman Judy Graham-Weaver said Saturday that the carrier had canceled seven Saturday flights and that afternoon flights from Atlanta would be delayed because of required de-icing of planes. AirTran too offered to waive ticket-change fees for some flights scheduled for this weekend and Monday in the South and Mid-Atlantic.

The Nashville area had an inch or so of snow overnight, and roads appeared to be clear. There was also snow in northern Alabama.

By Saturday morning, 4 to 5 inches of snow had fallen over several hours in Bowling Green, Ky., according to the Weather Service. Louisville had about an inch.

Louisville last had snowfall on Christmas in 2002, when a half-inch fell.

Snow was falling Christmas morning in Cleveland in northern Georgia.

"It's snowing, but there's none sticking yet," said Miranda Smith at the Kangaroo Express convenience store.

Snow wasn't expected in Atlanta until later in the day.

In parts of Tennessee, Georgia and the Carolinas, the snow was likely to be mixed with sleet and rain before turning entirely to snow. Temperatures in Georgia were expected to dip into the 20s on Christmas night, possibly leading to slick road conditions.

"If roads aren't able to dry up during the day, that's what will freeze up Saturday night into Sunday morning," said the weather service's Vaughn Smith in Atlanta.

Lon Anderson, a spokesman for AAA Mid-Atlantic, said people traveling by car on the East Coast over the holidays should check the weather forecasts.

"The fact is Mother Nature is going to be a big factor" in holiday travel, he said. "She's calling the shots this holiday season and in many places it will be very tough going." He said motorists should make sure their car is ready, especially their tires, and that they have enough windshield wiper fluid.

"It doesn't take much in the Mid-Atlantic area to cause mayhem," Anderson said.

In Minnesota, the storm brought 6 inches of snow Friday to Minneapolis and St. Paul. It pushed the monthly total there to 33.4 inches, topping the previous December record set in 1969.

The snow made traveling tough Friday in northeastern Iowa, where the bulk of the storm hovered. Cedar Rapids received more than 7 inches of snow.

Travelers could see airport screeners taking a closer look at empty insulated beverage containers like thermoses because air carriers were alerted about a potential terror tactic involving them, an administration official said.

The Air Transport Association was expecting 44.3 million people on U.S. flights between Dec. 16 and Jan. 5 - up 3 percent over the same period a year ago but still below pre-recession travel volume. The average ticket price was $421, up by 5 percent.

The AAA predicted overall holiday travel to rise about 3 percent this year, with more than 92 million people planning to go more than 50 miles by Jan. 2. More than 90 percent said they would be driving. Said Anderson of the storm: "The timing is really bad."

(Copyright 2010 by The Associated Press. All Rights Reserved.)