"Meteorologists were describing the storm as a “bomb cyclone,” in which masses of warm and cold air meet, creating a cyclonic effect."

"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 at times on Thursday as a storm packing winds gusting  to 90 miles an hour swept up 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."

Ellen Barry reports for the New York Times October 17, 2019. [2]