Dreaming of a White Christmas? You might be better off expecting a wet one instead.
A large storm system packing high winds and heavy rain is on track to sweep through the eastern half of the U.S. just in time to disrupt Christmas Eve travel plans, grounding flights and tying up traffic, meteorologists warn.
"It's really a wide-ranging storm system with several weather phenomena that could cause delays across the eastern portion of the country," Mike Musher, a National Weather Service meteorologist, told FoxNews.com on Tuesday. "Unfortunately, it's happening at one of the most-traveled days of the year."
In New York, light to moderate rainfall will give way into a soaking storm Christmas Eve, and rain was expected through the day in some New England states as well, Musher said.
The National Weather Service predicts Christmas Eve snow from Missouri to Michigan. Three inches of snow could fall in Chicago, where O'Hare and Midway airports are projecting around 4.2 million travelers throughout the holiday season, MyFoxChicago reported.
By Tuesday afternoon, FlightAware.com reported more than 3,600 flight delays in the U.S., with more than 600 flights canceled. Many of the affected flights were reported in New York, Philadelphia and Baltimore airports.
AAA expects 98.6 million Americans to travel 50 miles or more from home during the year-end holiday season, an increase of 4 percent from last year.
Musher said the storm system will begin clearing out on Christmas, though some areas of New England and the Great Lakes region may still suffer from rainfall. By the weekend, however, temperatures in the eastern part of the country will rise to five to 10 degrees above normal, and conditions will be sunny by Saturday, he said.
By Tuesday afternoon, heavy rain, accompanied by frequent lightning and damaging winds, was already falling in Atlanta, and MyFoxAtlanta.com reported that a tornado later in the day was "not out of the question." Severe thunderstorms with the potential of tornadoes had also developed in Georgia and Louisiana.
Meanwhile, severe storms have killed at least four people in Mississippi and damaged homes and businesses throughout the state, leading Gov. Phil Bryant to declare a state of emergency for two counties.
Bryant's office said thousands were without power Tuesday night around Columbia, which is about 80 miles southeast of Jackson.
Jones County Emergency Management director Marda Tullos said a man and woman were killed Tuesday inside a mobile home in the storm's path.
About 50 miles southwest, Marion County coroner Norma Williamson tells WDAM that two people were killed in Columbia.
Watches and warnings were out for a swath of Mississippi, Louisiana and Alabama with the storms moving toward Georgia, including Atlanta, and Florida late Tuesday into Christmas Eve.
Snow from another system fell in some Midwestern states Tuesday, including nearly 2 feet in South Dakota's Black Hills. Wind and blowing snow shut down eastern Colorado's Interstate 70 into Kansas.
FoxNews.com's Karl de Vries and The Associated Press contributed to this report.