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The Perfect Storm - Nor'easters

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The Perfect Storm

The Perfect Storm was a nicknamed coined by the National Weather Service to describe the Halloween Storm of October 1991. The Storm of the Century included the 8th unnamed hurricane since the practice of hurricane naming began in the 1950s.

NOAA

The Perfect Storm - Introduction to the Halloween Storm of the Century:

The Perfect Storm was a rare monster storm with an unnamed hurricane in the center of the tempest. The 'perfect storm' was a nickname given by Bob Case, a retired NOAA meteorologist, to this storm which began as an extratropical low on October 28, 1991. The storm became famous as author Sebastian Junger profiled the sinking of the swordfishing boat the Andrea Gail in the novel The Perfect Storm. The storm would eventually produce 100 foot rogue waves.

October Weather Makes Conditions Right for the Perfect Storm:

In October, most of the United States moves towards the cold winter months as the country slowly cools down from the summer heat. Ocean water has a high heat capacity meaning the landmasses of North America cool at a more rapid rate than the ocean waters. The heat retained in the Atlantic will often create massive storms in the still-warm waters. Because air masses retain the characteristics of their source, the continental air masses from the cooler land will often meet the maritime air masses of the warmer ocean creating large storms known as a Nor'easter.

Predicting the Perfect Storm:

Forecasters had a rough time forecasting this Halloween storm. The storm happened when a high pressure system, a low pressure system, and the remnants from Hurricane Grace collided in a trilogy of terror. The resulting waves and high winds hit many parts of the Eastern United States causing the famed sinking of the Andrea Gail and the death of her 6 passengers. An interesting aspect of the huge system was its retrograde motion (east to west) not away from the New England Coast, but toward it. Even while New Englanders were enjoying clear bright blue October weather, forecasters were warning of this immense storm.

A Rare Weather Event:

According to Bob Case, the set of meteorological circumstances leading to the storm happen only every 50-100 years. Much like the Fujiwhara Effect, several weather events (detailed at the bottom of the page) did a strange meteorological dance around each other. Storm damage hit as far south as North Carolina, Florida, and the Northern coast of Puerto Rico. The storm caused millions of dollars in damages to beaches and homes, including the seaside Kennebunkport, Maine home of former President George Bush.

An Unnamed Hurricane:

A remarkable event occurred when a hurricane formed inside the Halloween Nor'easter. Inside of the intense Halloween storm, wind speeds topped 80 mph making the storm of hurricane strength on the Saffir-Simposon Scale. This particular hurricane was never named as most tropical cyclones are named according to a pre-set list of hurricane names. Instead, it would become known as the Unnamed Hurricane of 1991. The storm finally broke up over Nova Scotia, Canada, on November 2, 1991 and remains only the 8th hurricane never to be named since the naming practice began in the 1950s.

Why Wasn't the Hurricane Named?:

There is a difference between the Halloween Storm of 1991 and the hurricane that formed inside the storm. At the time of the storm, emergency officials and the media were scrambling to get more information on the storm damages and well as any forecasts for future problems. It was decided that the hurricane would be short-lived and should remain unnamed so as not to confuse people.

Storm Records Broken:

Many locations up and down the Atlantic coast saw tide, flood, and storm surge records broken. In Ocean City, Maryland, a record high tide of 7.8 feet occurred beating the old record of 7.5 feet recorded during a March 1962 storm. Damages in Massachusetts topped $100 million dollars. Other specific facts are available from the National Climatic Data Center Damage Summary for the Perfect Storm.

Causes of the Storm of the Century:

The Ingredients for the Storm of the Century

  1. Hurricane Grace On October 27, 1991, Hurricane Grace formed off the coast of Florida. As Grace moved north on October 29, an extratropical cyclone formed over Canada. The counterclockwise motion of this low pressure zone left a trailing cold front over much of the Northern Atlantic coast. The cold front would later catch up with the dying hurricane. Grace would later make the retrograde turn to the east in response.
  2. A Low Pressure System The low pressure system formed over Canada and ran into Hurricane Grace off the coast of Nova Scotia tearing the already-downgraded hurricane apart. There was intense wind shear that acted as a hurricane-breaker, but the low pressure system absorbed much of the energy of Hurricane Grace. The low pressure system reached a peak intensity of 972 millibars of pressure and maximum sustained winds of 60 knots on October 30. The later movement of this low pressure system over warmer 80+ degree Gulf Stream waters served to intensify the storm in the same way tropical storms are intensified by warm ocean waters in the tropics.
  3. A High Pressure System A strong high pressure center extended from the Gulf of Mexico northeastward along the Appalachians into Greenland. Strong winds were generated from the tight pressure gradient between a strong high pressure center in eastern Canada (1043 mb) and the surface low.
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