Know the dangers of nor’easters

The phrase, “crowded coastline” might conjure up images of tanned tourists on the warm, sunny beaches of Florida and California. But, the most crowded coastal corridor in the United States stretches between Washington, D.C., and Boston — and includes the densely urban cities of Baltimore, Philadelphia and New York.

Moving image of a nor'easter, or major storm sytem.

Animation of April 2007 nor'easter.

(Credit: NOAA)

In this region, where 180 coastal counties support 77 percent of the area’s total population, the weather for more than half the year is far from warm and sunny. In fact, it’s the active season for a weather phenomenon known as nor’easters.

What Is a nor’easter?

A nor’easter 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.   

NOAA’s National Weather Service monitors potential nor’easters and all other types of weather conditions to provide you with the best information possible so you can effectively prepare for any type of threat.

The plan before the storm

Coastal flooding caused by nor'easter.

Coastal flooding caused by nor'easter.

High resolution (Credit: NOAA)

You can prepare for a nor’easter by taking the following actions:

The potential perils of coastal living

Damage from the 'Perfect Storm' in October 1991.

Damage from the 'Perfect Storm' in October 1991.

High resolution (Credit: NOAA)

As more people migrate to the coast each year, it’s important to understand the dangers of nor’easters, which include intense winds, high tides, beach erosion, flooding, freezing and heavy rain or snow.

New research has revealed that nor’easters often involve smaller, intense areas of snow within the larger zone of heavy rain that can extend 10 to 50 miles wide and 150 to 400 miles long. The snow areas can appear nearly stationary, often pivoting around a specific point as the storm gathers strength. It eventually moves toward the northeast, producing prodigious snowfall in the process.

Remember New York City during the blizzard of February 2006? A record 26.9 inches of snow fell on Central Park. The storm wrought havoc on mass transit, eventually bringing “the city that never sleeps” to a near standstill. 

A famous nor’easter occurred in 1991 off the coast of New England. Chronicled in the book The Perfect Storm (and later, the popular film), this storm surge produced widespread damage and erosion, hurricane-force winds, and 30- to 50-foot seas that killed six crewmembers of the Andrea Gail fishing vessel and six members of the Air National Guard who tried to save the helpless fishermen. NOAA estimated the cost of storm at nearly $1 billion.

To read more about the real “Perfect Storm,” visit NOAA’s Satellite and Information Service’s Web page.

Posted Feb. 7, 2013
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