A coastal storm may spread more than 7 inches of snow from northern New Jersey through central Massachusetts while sparing New York City any deep accumulations for the Thanksgiving holiday travel week.

A winter storm watch has been posted for Nov. 26 to Nov. 27 from northern New Jersey, including Morristown, through northeastern Pennsylvania and into Massachusetts and Connecticut, the National Weather Service said, warning that holiday driving could become “dangerous at times” as the snow falls. The agency predicted 7 to 10 inches (18 to 25 centimeters) in those areas, as well as in the Hudson River Valley to Albany and Glens Falls.

New York City will be spared the brunt of the storm.

“We are not expecting a significant snowfall in the city,” said Patrick Maloit, a weather service meteorologist in Upton, New York.

During the six-day Thanksgiving holiday period, from tomorrow through Nov. 30, the number of trips in the U.S. of 50 miles (80 kilometers) or more increases 54 percent, compared with the 23 percent jump from Christmas to New Year’s Day, according to the U.S. Department of Transportation.

Travel Busy

While airport and train travel often dominate the day before the holiday, when car trips are added to the total, Thanksgiving itself, Nov. 27 this year, is the busiest travel day, the department said.

An estimated 46.3 million travelers will make trips of 50 miles or more this Thanksgiving, the most since 2007, AAA said on its website. More than 89 percent of those journeys will be by car.

The latest storm will miss Buffalo, New York, said Tom Kines, a meteorologist with AccuWeather Inc. in State College, Pennsylvania.

The New York Thruway in western New York has reopened, according to the authority’s website. The highway had been closed during last week’s heavy snow around Buffalo.

The system will start as rain and light snow along the Eastern Seaboard on Nov. 26. It will rain in New York City through most of the day and then as the storm passes, the back side will change to snow. Areas to the west and north of the city might see 7 inches or more if the latest track holds.

NYC Thanksgiving

Maloit said Thanksgiving Day in New York City will have decreasing clouds and should be partly sunny with winds of 10 to 15 miles per hour, good conditions for the Macy’s Thanksgiving Day Parade parade.

The parade kicks off at 9 a.m. on 77th Street and Central Park West. The high for the day is forecast to be 41 degrees Fahrenheit (5 Celsius.)

Computer forecast models still aren’t clear on the exact track of the storm, which will determine the severity of any snowfall, said Steve LaVoie, a meteorologist with Hometown Forecast Services Inc. in Nashua, New Hampshire.

A track further inland will mean mostly rain for much of the Northeast, he said. There isn’t a scenario right now that would bring heavy snow to the major cities, including Boston and New York.

The most Boston will probably get is 1 to 3 inches, he said.

“Even if we had a worst-case scenario it’s not looking too bad,” LaVoie said.

Warm Waters

Another factor in making a forecast for exactly where the snow will fall is the relative warmth of the Atlantic Ocean, said Bill Simpson, a weather service meteorologist in Taunton, Massachusetts.

With Atlantic water temperatures hovering in the mid-40s, as opposed to the high 30s that would be normal for mid-winter, the ocean can keep the air near the shore warmer, raising the chance of rain.

“The snowline between Boston and Providence can be difficult to forecast because 1 degree either way can make a difference,” Simpson said.

In Washington, there may be a period of light snow at the end of the storm, said Andy Woodcock, a weather service meteorologist in Sterling, Virginia. He said it’s too early to forecast accumulations, although “my gut feeling” is that will depend on elevation.

Ski Outlook

With the heaviest snow forecast to fall inland, ski resorts throughout the Northeast should benefit, Kines said.

“Those areas will do very well,” Kines said. “It will make the ski operators happy.”

Farther to the west, temperatures are forecast to be about 3 to 5 degrees below normal from the upper Midwest to the U.S. Gulf Coast, said Matt Rogers, president of Commodity Weather Group LLC in Bethesda, Maryland. Readings may be nearer to normal on the East Coast and 5 to 8 degrees higher in the West.

Kines said Chicago may pick up some light snow during the next few days. No major storms are forecast. The only part of the country, outside of the Northeast, that may encounter difficulties from snow will be the northern Rocky Mountains, he said.