Flash flooding is possible overnight Tuesday into Wednesday on the East Coast.
A storm system is pushing across the eastern US ahead of Thanksgiving and is expected to deliver its most widespread and significant impacts on Tuesday, threatening to disrupt holiday travel with severe thunderstorms, drenching rain and snow.
At least two dozen states across the East, including major travel hubs from Atlanta to New York City, will contend with adverse weather during two of the busiest travel days of the year.
More than 27 million people from Mississippi to Virginia are at risk Tuesday for damaging storms spawned by the storm system, according to the Storm Prediction Center.
As Tuesday progresses, pouring rain and gusty winds are expected to expand into the mid-Atlantic before dumping a wintry mix of rain, sleet and snow on parts of the Northeast. The conditions may cause travel headaches during what is expected to be the busiest Thanksgiving travel period in years, leading to disruptions at airports in large hubs such as Atlanta, New York City, Boston and Washington, DC.
But there is still room for optimism. The storm's impacts are forecast to subside Wednesday as it tracks off the East Coast, leaving much of the central and eastern US to enjoy a dry Thanksgiving day.
The storm is expected to pummel the Southeast beginning Tuesday morning, bringing potentially damaging winds and possible tornadoes.
There's a slight risk, or Level 2 of 5 risk, for severe storms in parts of the Southeast, including southern Alabama and the western Florida Panhandle, where the threat is the highest, according to the storm center.
The risk for severe thunderstorms will shift east Tuesday afternoon and encompass portions of Georgia, the Carolinas and Virginia into early Wednesday morning. Damaging wind gusts are the main concern, but a few brief tornadoes cannot be ruled out.
Rain will also be heavy at times from southern Alabama to New Jersey.
Widespread rainfall totals of 1 to 3 inches are possible. Some areas, including Virginia's Blue Ridge Mountains, could receive over 4 inches.
The storm is also worsening fire weather in the drought- and wildfire-plagued Appalachians. Winds from the storm increased late Monday in the region and prevented steady, beneficial rain from reaching the ground. This caused one fire to flare up and force evacuations in a remote area of Tennessee near Great Smoky Mountains National Park.
A wintry mix of rain, sleet and snow will dampen elevated areas of Pennsylvania Tuesday morning and southern New York by Tuesday afternoon before pushing into parts of Vermont and New Hampshire in the evening.
High-elevation areas of the Adirondacks and the Green and White mountains are most likely to see accumulating snow Tuesday night.
As the sun rises in the northeast Wednesday, roads may be slick or snowy in parts of Vermont, New York and New Hampshire due to overnight snowfall.
The storm's impact will taper off significantly on Wednesday as it moves off the East Coast, dumping its final remnants on parts of New England. Snow will accumulate in Maine on Wednesday as a wintry mix continues across Vermont and New Hampshire.
Thanksgiving Day will be much cooler and largely dry across the central and eastern US as chilly Canadian air settles into place in the wake of the storm. A storm will begin to build over the northern Rockies on Thursday and strengthen on Friday bringing snow to portions of the Rockies, including Denver and Salt Lake City.
CNN's Andy Rose contributed to this report.
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