The big rush of traffic heading north for the holiday weekend is expected to get underway Wednesday afternoon as drivers who apparently hoped to wait out the miserable weather begin to set out for their Thanksgiving destinations.

Tracking data from Inrix, the company which supplies many of the world’s frontline traffic reports, shows that the exodus to places south and west of the Washington region began early this morning, but traffic headed north has been about the same as last Wednesday.

“What are we seeing as we compare this morning to a week ago Wednesday, which was a typical day: big spikes westbound and southbound but not northbound 95 until the afternoon,” said Jamie Holter, a traffic analyst with Inrix.

The Inrix data also showed that a lot of people headed out of town on Tuesday in an apparent effort to beat the storm.

The busiest travel day of the year got off to a miserable start along much of the East Coast Wednesday, with high winds, cold temperatures and heavy precipitation forecast for most of the day.

On the eve of the busiest travel day of the year, Americans catch earlier flights ahead of a winter storm's arrival in the Northeast. (REUTERS)

The combination of unfriendly weather and the crush of passengers — across the nation, more than 3 million plan to fly during this holiday weekend — caused delays at several East Coast airports early Wednesday and threatened to destabilize the air travel system nationwide.

While no delays were reported at Dulles International or Reagan National, the region’s busiest airport, Baltimore Washington Thurgood Marshall International, was reporting departure delays of 45 minutes due to traffic volume as of 8:45 a.m.

The most worrisome signal of things to come was out of New York, where all three major airports — JFK, LaGuardia and Newark — were telling inbound planes to postpone departure from other cities for up to an hour because New York was being hit with high winds. Similar problems in Philadelphia also were delaying inbound flights. The delays weren’t quite so long — 35 minutes — in Atlanta, but that airport is the nation’s busiest, so delays there did not bode well.

All four of those airports are hubs for passengers who want to switch planes to other destinations. Such delays usually mean that passengers miss their connecting flights, and the impact ripples through other airports.

More than 43 million Americans say they plan to spend Thanksgiving away from home — and more than a million of those travelers say they intend to head out from the Washington area.

David Buck, a spokesman at the Maryland State Highway Administration, said traffic was heavy on the major roadways leaving the District and its Maryland suburbs, but there were no major accidents or problems and congestion seemed typical given the inclement weather and the holiday.

In Virginia, a multi-car accident on southbound Interstate 95 in Prince William County created a four-mile traffic jam by 8 a.m.

A few secondary roads in Maryland were closed overnight because of flooding but reopened before daybreak, Buck said.

With 72,900 people from Washington planning air travel over the holiday, and millions more scheduled to arrive from elsewhere or pass through the region’s three major airports, even a dry day would have been likely to result in delays.

Dry it is not.

In the Washington area, authorities reported wet, slick roads, but no backups, except for the approaches to Baltimore’s harbor tunnels. Forecasters say temperatures will drop as the day progresses. Rain showers will become intermittent, but if there is lingering precipitation it could become snow or sleet in the afternoon. The chance of the precipitation impacting roads in the Washington area is small, The Washington Post’s Capital Weather Gang said.

Drier, colder and windier weather is expected by Wednesday night, when those who have to work during the day are likely to take to the roads.

Buck, from the Maryland highway agency, said that over the past decade, many travelers have started to “spread out when they leave” for Thanksgiving, in some cases setting out as early as the Sunday or Monday before the holiday.

He said it was tough to figure out if more travelers had left earlier than they had planned this year, in hopes of beating the heavy rain that descended on the Washington area overnight, and the sleet and snow that was pelting parts of Ohio, Pennsylvania and upstate New York.

Some travelers may choose to delay their departure until the skies clear, Buck said. With rain trailing off by mid-morning, he predicted traffic jams at midday, sparked by an exodus of travelers hoping to get on the road before a new round of precipitation threatens to create more slick roads in some areas.