Dangerous Nor’easter Plows Toward East Coast

A sprawling winter storm barreled toward the Atlantic Coast on Thursday and was expected to pound most of it with a potent mix of rain, snow, gusty winds and storm surge that forecasters warn could flood neighborhoods, knock out power and destroy homes.

“Take this storm seriously!” the National Weather Service’s Boston branch warned on Twitter late Thursday afternoon. “This is a LIFE & DEATH situation for those living along the coast.”

The effects of the nor’easter, which could linger through Saturday or beyond, are expected to stretch as far south as Georgia and South Carolina, all the way north to Maine. Weather officials say 10 inches of snow — or perhaps more — could blanket parts of New York; some areas of New England could get 3 to 4 inches of rain; and some coastal towns are expected to be hit with hurricane-force winds of 50 mph or more.

Alerts have been issued up and down the coast, but experts are warning that some of the most severe flooding could occur in places like Cape Cod, Nantucket and Martha’s Vineyard in Massachusetts where the Weather Service said roads, basements and other structures could become inundated by 3 feet of water or more. In those areas, officials said, the most severe coastal flooding was likely to occur during the high tides Friday night and Saturday afternoon.

“Some neighborhoods may be cut off for an extended time,” the Weather Service said in a written warning. “This is a dangerous storm, and evacuation of some neighborhoods may be necessary.”

The dire messages prompted Gov. Andrew M. Cuomo of New York to activate the state Emergency Operations Center on Thursday. Also Thursday, Gov. Charlie Baker of Massachusetts said he had called in the National Guard, noting that the flooding in his state was predicted to be even more severe than what occurred during a storm in January.

“Do not ride out the storm if you are told to evacuate,” he said at a news conference.

The Jan. 4 storm gained much attention in part because some meteorologists described it as a “bomb cyclone.” (The name essentially derives from how quickly the barometric pressure falls.) Meteorologists say the pressure in the center of this weekend’s storm will plummet so fast that it, too, is likely to become a bomb cyclone.

The expected conditions are so worrisome that some airlines, like Delta and Southwest, have put out warnings about the weather’s impact on flights and are allowing travelers to change their Friday and Saturday reservations.

The Port Authority of New York and New Jersey said Thursday that it had taken “significant measures” to prepare for the storm. Officials plan to provide busing in the event that service on AirTrain Newark or AirTrain JFK is suspended because of high winds. And at La Guardia Airport, employees have secured the cranes and other construction equipment that was being used as part of a redevelopment program. They say they will redeploy it as needed.