By Ashley Halsey III
Washington Post Staff Writer
Thursday, December 24, 2009; B05
People waiting to make a last-minute dash out of town Christmas morning may face the region's two most cursed weather words: wintry mix.
Thousands of Washington area drivers had relatively smooth going as they made their escape Wednesday, but the weather window for comfortable winter travel is expected to slam closed on Christmas morning.
After more than 24 hours of subfreezing temperatures, a rain-sleet mix could fall on frozen pavement and turn to ice faster than salt trucks can get to it.
"We're hopeful it falls as rain. Wouldn't that be great?" said Karyn LeBlanc, spokeswoman for the District Department of Transportation. "But we're encouraging people who are going to visit family or friends to go the night before."
The Christmas morning forecast calls for ground-level temperatures several degrees below freezing, but warmer temperatures at higher elevations mean that precipitation will emerge from the clouds as rain.
"That's a recipe for ice," said Jason Samenow, chief meteorologist for the Capital Weather Gang. "It's looking like an icy mix at least until noon, and as you go west into the Shenandoah Valley it may last into the afternoon."
Samenow said the approaching storm was large enough to drop an inch of rain, which could combine with melting snow to cause flooding in some places.
With road crews exhausted by days of 12-hour shifts, highway officials were eyeing that forecast and trying to clear snow from drains.
"Our concern would be that with all the snow still out there, an inch of rain would cause flooding," said Charlie Gischlar of the Maryland State Highway Administration. "We've got people out there right now clearing drainage areas so the rain and melting snow have some place to go."
LeBlanc said a coating of ice on unshoveled sidewalks would make them doubly treacherous, and she urged property owners to clear sidewalks before the big snow becomes the big freeze.
Although traffic was slow in spots on Interstate 95 north and south of the Capital Beltway on Wednesday, the flow suggested that many of the 2.2 million drivers expected to depart for the holidays had left already or were waiting until Thursday.
But if most Washington drivers were having a relatively easy time three days after the big snow, people leaving by plane and those headed to New York and New England by train appeared to have more to worry about.
Last-minute air travelers headed west were running headlong into a blizzard that was causing delays at major air hubs that handle flights throughout the West and Midwest. Chicago's O'Hare International Airport was averaging 2 1/2 -hour delays Wednesday evening.
"That's going to be a major problem," said John B. Townsend, mid-Atlantic spokesman for the American Automobile Association. "When you have this level of travel, you're going to have delays, delays, delays. It's not going to be a pretty picture."
Many major airlines -- including United, American, US Airways, AirTran and Southwest -- were offering to waive fees normally charged passengers who change their plans. United operates a major transfer point for fliers at O'Hare, and it said extra booking fees would be waived for passengers traveling to or from Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota and Wisconsin.
According to AAA, 117,000 people in the Washington area were planning to fly somewhere to celebrate the season. Nationwide, 4.2 million people were expected to travel by air for the holidays.
The Washington region's three major airports Wednesday reported that all runways were cleared of snow and in operation. Terminals were packed with customers. The airports said ground transportation delays that left hundreds of people stranded at airports had been resolved.
But thousands of train passengers were frustrated Wednesday when a low-voltage problem in northern New Jersey cut off power in a tunnel under the Hudson River. That forced Amtrak to halt trains into and out of New York's Penn Station about 8:45 a.m. Wednesday, railroad spokesman Clifford Cole said.
The problem affected service as far south as Washington and as far north as Boston. At least one train scheduled to depart Washington's Union Station was canceled. Power was restored about 11:30 a.m., and Amtrak was investigating the cause.
In the immediate aftermath of last weekend's storm, many service stations in the Washington area ran out of gas as tank trucks were snowed in along with everyone else.
Michael Fox, a spokesman for the Gasoline & Automotive Service Dealers of America, said that dealers keep inventories low when wholesale fuel prices are falling and that they got caught short after the storm.
Gas is available at the Maryland House and Chesapeake House service areas on I-95 in Maryland, said Teri A. Moss of the Maryland Transportation Authority.
Those service areas have Sunoco and Exxon fuel pumps. Moss said the Exxon pumps are out of premium gas but have regular gas. She said Sunoco had all octane levels.
"It shouldn't be a problem," Moss said. "There's plenty of gas."
Staff writer Sholnn Freeman and the Associated Press contributed to this report.