Northeast storm: Powerful winds knock out power to 500,000

BOSTON — Utility poles snapped, cruise ships sought shelter, boats broke from their moorings, trees were uprooted, and more than 500,000 customers in New England were without power early Thursday as winds gusting up to 90 miles an hour swept the East Coast.

Meteorologists described the storm as a “bomb cyclone,” sometimes known as a “winter hurricane,” which occurs when atmospheric pressure drops especially dramatically — by 24 millibars in 24 hours.

A bomb cyclone can happen when a mass of warm air meets with a mass of cold air, and the air starts to move, with the rotation of the earth creating a cyclonic effect. The direction is counterclockwise in the Northern Hemisphere, leading to winds that come out of the northeast — a Nor’easter.

The storm strengthened quickly as it moved up the coastline, and atmospheric pressure dropped from 1,000 millibars to 974 millibars, said Benjamin Sipprell, a meteorologist based in Boston for the National Weather Service.

A pressure drop of that kind can even affect the human body, causing headaches or flare-ups in preexisting injuries, he said.

The highest winds, of 90 mph, were recorded early Thursday in Provincetown, Mass., and gusts of 70 and 80 mph were buffeting parts of Cape Cod, according to Christopher Besse, a spokesman for the Massachusetts Emergency Management Agency.

As of 8:15 a.m., around 225,000 customers in Massachusetts were without power, mostly because trees or tree limbs had crashed down, snapping power lines.

Firefighters in Duxbury, around 35 miles southeast of Boston, published photographs of numerous trees that had crashed onto roads and the roofs of houses.

In Maine, two cruise ships, the AIDAdiva and the Mein Schiff 1, sought shelter in Portland Harbor on Wednesday as the storm approached,...