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The 1991 Perfect Storm, also known as the The No-Name Storm (especially in the years immediately after it took place), was a nor'easter that absorbed Hurricane Grace and ultimately evolved back into a small unnamed hurricane late in its life cycle. The initial area of low pressure developed off Atlantic Canada on October 29. Forced southward by a ridge to its north, it reached its peak intensity as a large and powerful cyclone. The storm lashed the east coast of the United States with high waves and coastal flooding before turning to the southwest and weakening. Moving over warmer waters, the system transitioned into a subtropical cyclone before becoming a tropical storm. It executed a loop off the Mid-Atlantic states and turned toward the northeast. On November 1 the system evolved into a full-fledged hurricane with peak winds of 75 miles per hour (120 km/h), although the National Hurricane Center left it unnamed to avoid confusion amid media interest in the predecessor extratropical storm. It later received the name "the Perfect Storm" (playing off the common expression) after a conversation between Boston National Weather Service forecaster Robert Case and author Sebastian Junger. The system was the fourth hurricane and final tropical cyclone in the 1991 Atlantic hurricane season. The tropical system weakened, striking Nova Scotia as a tropical storm before dissipating. Damage from the storm totaled over $200 million (1991 USD) and the death toll was thirteen. Most of the damage occurred while the storm was extratropical, after waves up to struck the coastline from Canada to Florida and southeastward to Puerto Rico. In Massachusetts, where damage was heaviest, over 100 homes were destroyed or severely damaged. To the north, more than 100 homes were affected in Maine, including the vacation home of then-President George H. W. Bush. More than 38,000 people were left without power, and along the coast high waves inundated roads and buildings. In portions of New England, damage was worse than that caused by Hurricane Bob two months earlier. Aside from tidal flooding along rivers, the storm's effects were primarily concentrated along the coast. A buoy off the coast of Nova Scotia reported a wave height of , the highest ever recorded in the province's offshore waters. In the middle of the storm, the ''Andrea Gail'' sank, killing its crew of six and inspiring the book, and later movie, ''The Perfect Storm''. Off the shore of New York's Long Island, an Air National Guard helicopter ran out of fuel and crashed; four members of its crew were rescued, and one was killed. Two people died after their boat sank off Staten Island. High waves swept two people to their deaths, one in Rhode Island and one in Puerto Rico, and another person was blown off a bridge to his death. The tropical cyclone that formed late in the storm's duration caused little impact, limited to power outages and slick roads; one person was killed in Newfoundland from a traffic accident related to the storm. ==Meteorological history== The Perfect Storm originated from a cold front that exited the east coast of the United States. On October 28, the front spawned an extratropical low to the east of Nova Scotia. Around that time, a ridge extended from the Appalachian Mountains northeastward to Greenland, with a strong high pressure center over eastern Canada. The blocking ridge forced the extratropical low to track toward the southeast and later to the west. Hurricane Grace was swept aloft by its cold front into the warm conveyor belt circulation of the deep cyclone on October 29. The cyclone significantly strengthened as a result of the temperature contrast between the cold air to the northwest and the warmth and humidity from the remnants of Hurricane Grace. The low pressure system continued deepening as it drifted toward the United States.〔 It had an unusual retrograde motion for a nor'easter, beginning a set of meteorological circumstances that occur only once every 50 to 100 years. Most nor'easters affect New England from the southwest. While situated about south of Halifax, Nova Scotia, the storm attained its peak intensity with winds of up to . The nor'easter reached peak intensity at approximately 12:00 UTC on October 30 with its lowest pressure of 972 millibars. The interaction between the extratropical storm and the high pressure system to its north created a significant pressure gradient, which created large waves and strong winds.〔 Between the southern New England coast and the storm's center, the gradient was .〔 A buoy located south of Halifax reported a wave height of on October 30. This became the highest recorded wave height on the Scotian Shelf, which is the oceanic shelf off the coast of Nova Scotia.〔 East of Cape Cod, a NOAA buoy located at reported maximum sustained winds of with gusts to , and a significant wave height (average height of the highest one-third of all waves) of around 15:00 UTC on October 30. Another buoy, located at , reported maximum sustained winds of with gusts to and a significant wave height of near 00:00 UTC on October 31.〔 Upon peaking in intensity, the nor'easter turned southward and gradually weakened; by November 1, its pressure had risen to . The low moved over warm waters of the Gulf Stream, where bands of convection around the center began to organize. Around this time, the system attained subtropical characteristics. On November 1, while the storm was moving in a counter-clockwise loop, a tropical cyclone had been identified at the center of the larger low. (Although these conditions are rare, Hurricane Karl during 1980 formed within a larger non-tropical weather system.) By around 14:00 UTC on November 1, an eye feature was forming, and the tropical cyclone reached its peak intensity with maximum sustained winds of ; these estimates, combined with reports from an Air Force Reserve Unit flight into the storm and confirmation that a warm-core center was present, indicated that the system had become a Category 1 hurricane on the Saffir–Simpson Hurricane Scale. The hurricane accelerated toward the northeast and quickly weakened back into a tropical storm. It made landfall near Halifax, Nova Scotia, at 14:00 UTC on November 2 with sustained winds of . While the storm was approaching the coast, weather radars depicted curved rainbands on the western side of the system.〔 After crossing over Prince Edward Island, The storm fully dissipated late on November 2.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「1991 Perfect Storm」の詳細全文を読む スポンサード リンク
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