Holiday Travel Headache Awaits Millions As 43 million Americans prepare to travel for Thanksgiving this week, some will have to brave snow, wind and heavy rain as they trek to their holiday destinations. Bad weather will cause a rough start for some travelers expected to be on the move this week, 90 percent of whom will be travelling in cars. Snow is forecast for mountain passes in Washington state by Thanksgiving, and heavy flooding in Northern California is already creating dangerous road conditions in the West. A closed vortex will drop over the Northeast Pacific and move slowly southward, bringing in the wet and soggy conditions to the region, according to the National Weather Service. In the areas with highest terrain, temperatures are forecast to be low enough to support snow, creating rough conditions for motorists. "Thirty-nine million people will be traveling in cars, so interstates and the roads are going to be very busy," Michael Green, AAA Spokesman told ABC News. In the air, very few delays are expected, as the airlines are looking forward to clear weather for the week. Mother nature looks to deliver a beautiful weather week for holiday travel. Let's do this," airline Jet Blue tweeted. But air travel is actually down 3 percent this Thanksgiving, mainly because airlines have cut the number of flights, and prices are high. The busiest day for travel will be Wednesday when 45 percent head out, with 35 percent returning home on Sunday, and 25 percent waiting until Monday.