BOSTON — A powerful, fast-moving storm swept into the northeast U.S. on Thursday with the potential for more than a foot of snow along the Philadelphia-to-Boston corridor.

Commuters faced windblown snow and slick highways. Forecasters said Thursday’s weather had the potential to be the most powerful storm that some areas have seen in a mostly snow-free winter. Schools were closed in Albany, New York City, Philadelphia and Boston, numerous accidents were reported and more than 3,000 flights were cancelled.

The National Weather Service predicted that the Boston area and eastern Maine could get 12 to 18 inches of snow, and a blizzard warning has been issued for all of Long Island until 6 p.m. New York City could see eight to 12 inches and the Philadelphia area four to eight inches. Near whiteout conditions were possible, with the snow expected to fall at a clip of two to four inches per hour at its peak.

Airlines scrapped thousands of flights by late Wednesday as a precaution, and FlightAware.com reported 3,323 flights were cancelled Wednesday through Friday, including more than 2,700 on Thursday.

Officials also warned of high winds, coastal flooding and possible power outages.

Massachusetts activated its emergency management bunker in Framingham, where Gov. Charlie Baker was scheduled to provide updates on the storm at midday. Baker urged people to stay off the roads to allow plows and sanders to do their work.

Eastern Long Island braced for up to 16 inches of snow, with a potential for power outages. “The roads are in bad shape … covered and icy,” Suffolk County Police Commissioner Tim Sini said. He said snow was falling at up to two inches per hour and was expected to intensify.

New York City Mayor Bill de Blasio said people should stay home.

“If you need to go out, please, don’t use your car,” de Blasio said on NY1 television.

In Manhattan, intrepid, bundled-up commuters carefully navigated snow-covered sidewalks and blowing snow stung any exposed skin.

New Jersey’s emergency management office reported about 50 accidents before midmorning, and that number was expected to grow. New Jersey Transit trains face delays of up to 15 minute.

State offices in New Jersey were closed, as were the courts in Massachusetts. Government offices in the Delaware, Bucks, Chester and Montgomery counties surrounding Philadelphia were also shuttered.

Thursday’s storm was expected to last six to 10 hours, said Carl Erickson, a senior meteorologist with AccuWeather in State College, Pennsylvania.

The snow was expected taper off by the early afternoon in the Philadelphia and New York City areas, but New Englanders were bracing for snowfall through the evening commute.