The storms discussed above occurred on the West Coast of the U.S., but what about similar storms that form on the East Coast? When similar storms form along the eastern seaboard, they can often grow into monster storm systems that have wide-ranging impacts. When they do develop, they are termed nor’easters. In most storm formation scenarios, warm moist air masses originating from the Gulf of Mexico move north and east. They then collide with cold fronts originating from Arctic Canada that push south. In many cases, the warm air masses form ridges of high pressure that form on either side of a cold air trough. When the air masses collide, low pressure develops as the warm air mass on the leading side of the trough is forced upward.
Like tropical cyclones, these storms can actually intensify when they are fueled by warm water. In the case of nor’easters, when the low-pressure system moves over the mid-Atlantic coast, they often intersect air masses fueled by the warm Gulf Stream. This warm water produces moisture-laden air that rises rapidly when displaced by the denser cold air and helps to strengthen the convective uplift. By pumping additional warm, moist air into the atmosphere, these storm systems can become stronger, often with gale force winds, and intensive precipitation. As most of these storms occur in the winter, they often result in significant snowfall inland and have intensive coastal impacts with high waves and intensive erosion. Each year, nor’easters can be relatively minor or can be very severe.
This video (2:30), What is a Nor'easter, helps explain how these types of storms form.
In this silent animation (0:45), Satellite View of February Nor'easter, produced by NASA’s Goddard Space Flight Center using NOAA’s GOES satellite, you can see how a nor’easter formed in February 2013 when New England and much of the U.S. Northeast was impacted by heavy snowfall, ice, and high winds. There is no narration with this animation.
By carefully watching this video, you can follow water vapor that originates in the Gulf of Mexico and a series of cold fronts that move east from the central U.S. As this water vapor moves off the mid-Atlantic, the air masses collide and intensify into a well-organized counter-clockwise rotating low-pressure cell that brings much of the moisture at high altitude back over land from the northeast. As the center of circulation is located along the New Jersey coast, the rotation brings intensive winds out of the northeast to the New England coastline.