nor'easter

thumb|upright=1|Nor'easter off the New England coast of the United States responsible for the January 2018 North American blizzard

A '''nor'easter (also northeaster'''; see below) is a large-scale extratropical cyclone in the western North Atlantic Ocean. The name derives from the direction of the winds that blow from the northeast. Typically, such storms originate as a low-pressure area that forms within of the shore between North Carolina and Massachusetts. The precipitation pattern is similar to that of other extratropical storms, although nor'easters are usually accompanied by heavy rain or snow, and can cause severe coastal flooding, coastal erosion, hurricane-force winds, or blizzard conditions. They tend to develop most often and most powerfully between the months of November and March, because of the difference in temperature between the cold polar air mass coming down from central Canada and the warm ocean waters off the upper East Coast. The susceptible regions—the upper north Atlantic coast of the United States and the Atlantic Provinces of Canada—are generally impacted by nor'easters a few times each winter.