BOSTON — High wind and soaking rain will sweep coastal regions of the Northeast Tuesday, threatening to tie up air traffic and send holiday decorations flying.

Flood watches and advisories stretch from Maine to Virginia in advance of a storm shaping up in the western Atlantic, the National Weather Service said. Snow may fall from northeastern Pennsylvania to Maine, which is covered by a winter storm watch.

“Most of the strongest impacts from this storm will start around daybreak,” said Tim Morrin, a weather service meteorologist in Upton, New York. For New York City, “we’re not expecting any snow, it’s a rain event.”

As much as 2 inches of rain may fall in New York starting about 6 a.m., possibly causing flooding in areas where there’s poor drainage. Gusts of 45 to 55 miles per hour are forecast.

The winds may cause air traffic delays and knock down holiday decorations, Morrin said. The weather service is warning people to take extra care securing things that aren’t normally outside, such as lights and holiday displays.

Rain will begin in Washington later Monday with the chance of showers continuing through Dec. 10, the weather service said. Philadelphia may get some snow, with little accumulation. Snow showers are forecast for Boston through Monday.

Rob Carolan, a meteorologist at Hometown Forecast Services Inc. in Nashua, New Hampshire, said warmer air will push into the coast later today, turning any snow into rain later. There’s a chance that upstate New York and the northern New England states of Vermont, New Hampshire and Maine could get as much as 12 inches of snow.

“Somebody is going to get buried,” Carolan said. “Someone is going to have over a foot of snow from Berkshires, the Adirondacks, the Green Mountains, the White Mountains.”

While New York City may see some flakes during the course of the week, there shouldn’t be any accumulation, he said.

The wind advisory will end tomorrow at 6 p.m. in New York while the flood watch runs until 1 a.m. the day after. The alerts end overnight tomorrow for coastal New England.

A large upper-level low-pressure system will capture the storm and keep it lingering around the Northeast through much of the week, meaning New York and Boston may not see sun until the weekend.

As more unsettled weather comes across the United States, there’s a chance another storm may form in the Atlantic south of Massachusetts.