What is a Nor”Easter? It is a cyclonic storm that moves along the east coast of North America. It’s called “nor’easter” because the winds over coastal areas blow from a northeasterly direction.
Nor’easters may occur any time of the year, but are most frequent and strongest between September and April. These storms usually develop between Georgia and New Jersey within 100 miles of the coastline and generally move north or northeastward.
Nor’easters typically become most intense near New England and the Canadian Maritime Provinces. In addition to heavy snow and rain, nor’easters can bring gale force winds greater than 58 miles per hour. These storms can produce rough seas, coastal flooding and beach erosion.
The East Coast of North America provides an ideal breeding ground for nor’easters. During winter, the polar jet stream transports cold Arctic air southward across the plains of Canada and the U.S., and eastward toward the Atlantic Ocean, as warm air from the Gulf of Mexico and the Atlantic tries to move northward. The warm waters of the Gulf Stream help keep the coastal waters relatively mild during the winter, which in turn helps warm the cold winter air over the water. This difference in temperature between the warm air over the water and cold Arctic air over the land is the area where nor’easters are born.
– Source: http://www.noaa.gov/features/03_protecting/noreasters.html