On the fourth day of Christmas, Washington may get the gift it likes the least, snow.

If a Canadian cold front meets up with an eastbound Mississippi low-pressure system along the Pennsylvania-Maryland border, as the U.S. Weather Service predicts, Washington could see snow by late this afternoon.

A winter storm watch is in effect for tonight.

Highs today will reach the mid- to upper 30s, and according to the weather service, there is a 90 percent chance of rain and sleet changing gradually to snow as the day wears on.

"Looks like it's going to be messy" during the evening rush hour, forecaster Steve Hogan said early today.

While area residents kept their eyes on the weather forecast, holiday travelers flocked to area airports yesterday afternoon and National and Dulles International airports reported a severe shortage of parking spaces.

"Roadways are becoming very congested at both airports this evening, especially at the main terminal at National," said Dave Hess, spokesman for the airport authority.

Hess said additional police were on duty to help move traffic.

At Baltimore-Washington International Airport, the operations office reported that ground traffic was moving smoothly and parking was still available.

On the highways, police reported that traffic was heavy but moving through the Washington-Baltimore corridor.

Traffic deaths continued to mount in Virginia, where seven motorists and one pedestrian were reported killed between 6 p.m. Dec. 23 and 6 p.m. yesterday, state police said.

Last year, Virginia reported 11 highway fatalities during the Christmas holiday.

Police reported five deaths on Maryland roads, the most recent in downtown Baltimore where a paramedic was killed when her car collided with a transit bus yesterday.