Nor'easters and Alberta Clippers
moved quite differently than indicated by their main wind direction. He reasoned that his "eclipse storm" had come from the south or southwest rather than the northeast. While Franklin never fully grasped the cyclonic flow pattern, he did realize that storms often moved in directions other than that of their winds.
Satellite view of a Nor'easter aka "The Perfect Storm"
Courtesy NOAA
Nor'easters have become legendary along the Atlantic Coast for their fury and impacts. The Blizzard of '[18]88 and The Perfect Storm are two prime examples. Most nor'easters arise from cold-season storm systems that first move through the Ohio Valley or Gulf States to a position off the Atlantic Coast. There, many receive a regeneration of intensity when they encounter the warmer ocean waters, particularly if the Gulf Stream waters are involved. When conditions are ideal, the storms become bomb cyclones, a term relating to a sudden and dramatic deepening of the central pressure, at a rate equal to or exceeding 1 millibar per hour over a 24-hour period. The suddenness of a bomb cyclone's fury is matched only by the resulting winds and precipitation.
Nor'easters generally hug the coast as they move north. Their northeast storm winds rush off the ocean with unbridled fury. The wind flow pattern also permits the storm to pick up relatively warm and very moist air from the ocean which it drops when meeting colder air on the western side of the system. If the air is cold enough, the precipitation falls as snow, at times measured in feet rather than inches -- merging blizzard with nor'easter.
The Alberta Clipper
While Nor'easters are creatures of the East Coast, many are born in the lee of the Rocky Mountains. There are two prime mid-continent spawning grounds for storm systems. One is around the State of Colorado; the other the Province of Alberta. Those systems born around Colorado are simply called Colorado Lows. Storms born in Alberta (perhaps reborn is a better concept as many arise from the remnants of Gulf of Alaska lows weakened in crossing the Rockies) possess unique characteristics that have led to the handle Alberta Clippers as they move swiftly out of the Canadian Prairies, like the Clipper sailing ships of old, bringing frigid weather to the east.
Alberta Clippers form on Alberta's high plains east of the Canadian Rockies. Once organized, they "sail" southeastward under the push of a northwesterly jet stream into Montana and the Dakotas, then turn across the Great Lakes basin headed toward the Atlantic Coast. This track, however, leaves them far from the moisture sources
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