Nor'easters can occur in the eastern United
States any time between October and April, when moisture and cold air are
plentiful. They are known for dumping heavy amounts of rain and snow,
producing hurricane-force winds, and creating high surfs that cause severe
beach erosion and coastal flooding. A Nor'easter is named for the winds
that blow in from the northeast and drive the storm up the east coast
along the Gulf Stream, a band of warm water that lies off the Atlantic
There are two main components to a Nor'easter:
- Gulf Stream low-pressure system - (counter-clockwise winds)
These systems generate off the coast of Florida. The air above the Gulf
Stream warms and spawns a low-pressure system. This low circulates off
the southeastern U.S. coast, gathering warm air and moisture from the
Atlantic. Strong northeasterly winds at the leading edge of the storm
pull it up the east coast.
- Arctic high-pressure system - (clockwise winds) As the strong
northeasterly winds pull the storm up the east coast, it meets with
cold, Arctic air blowing down from Canada. When the two systems collide,
the moisture and cold air produce a mix of precipitation.
Winter conditions make Nor'easters a normal occurrence, but only a handful
actually gather the force and power to cause problems inland. The
resulting precipitation depends on how close you are to the converging
point of the two storms.
|March 1993 ("Blizzard of '93")
||Snow, tornadoes and flooding from Alabama to
Maine; damages in excess of $1 billion
||More than 1,000 homes damaged from the Carolinas
|President's Day 1979
||Shut down Washington, D.C.
|Ash Wednesday 1962
||Northeast coastline hit for five days
A powerful Nor'easter can bring travel to a
standstill, closing city streets and making it nearly impossible to get
anywhere for days. The thing to remember with Nor'easters is that the
storm systems occur frequently, but only a few of them are powerful enough
to make it into the news. There are two types of Nor'easters:
- Offshore forming - These are the storms you hear about in the
news. It is a news-worthy storm that moves east of east-coast cities,
dumping lots of heavy snow. In an offshore-forming storm, the hardest
hit metropolitan areas are likely to be Washington D.C, Philadelphia,
New York City and Boston. Eventually, the system moves far enough north
that the Canadian jet stream pushes it off the coast.
- Onshore forming - These storms are less exciting than the
offshore-forming storms. They move west of east-coast cities, with
gusting winds and mostly rain.