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Hurricane Bill was a large Atlantic tropical cyclone that wrought minor damage across mainly Atlantic Canada and the East Coast of the United States during August 2009. The second named storm, first hurricane, and first major hurricane of the annual hurricane season, Bill originated from a tropical wave in the eastern Atlantic on August 15. Initially a tropical depression, the cyclone intensified within a favorable atmospheric environment, becoming Tropical Storm Bill six hours after formation. Steered west-northwest around the southern periphery of a subtropical ridge to the northeast of the cyclone, Bill passed through the central Atlantic. At 0600 UTC on August 17, the cyclone strengthened into a Category 1 hurricane on the Saffir–Simpson hurricane wind scale; within 36 hours, Bill entered a period of rapid deepening and intensified into a major hurricane with winds of 115 mph (185 km/h). Passing well northeast of the Lesser Antilles, Bill attained its peak intensity with maximum sustained winds of 135 mph (215 km/h) and a minimum barometric pressure of 943 mb (hPa; 27.85 inHg) on August 19 and August 20, respectively. Thereafter, an approaching trough induced higher vertical wind shear across the region, causing slow weakening of the hurricane; this same trough resulted in an accelerated motion and curve northward. As the storm passed Bermuda, it contained sustained winds equal to a Category 2, and remained a hurricane through landfall on the coast of Newfoundland. After moving inland and weakening to a tropical storm, Bill began an extratropical transition; this alteration in structure was completed by 1200 UTC on August 24. Two days later, Bill's remnant low was absorbed into a larger extratropical system over the Northern Atlantic.〔 Bill caused $46.2 million in damages and two deaths over a nine-day period. As it passed close to Bermuda, the hurricane caused power outages and strong winds, though damage was minor. Despite remaining well offshore of the United States East Coast, the storm's large wind field contributed to strong surf which caused severe beach erosion. Numerous offshore rescue operations occurred as a result of people swept away by the strong waves. All two deaths caused by the hurricane were the result of drownings off the U.S. coast. In some areas of New England, the storm's outer rainbands caused flash flooding. In Atlantic Canada, Bill caused mainly power outages and flooding events. Several roads were flooded in Nova Scotia, and 32,000 people lost power. In Newfoundland, where the hurricane made landfall, strong winds caused minor tree damage. As an extratropical system, Bill dropped light rainfall in the British Isles and Scandinavia. ==Meteorological history== A tropical wave moved off the western coast of Africa on August 12, 2009, and entered the Atlantic Ocean. The National Hurricane Center (NHC) remarked upon the possibility for tropical cyclone development, as the wave had already been accompanied by a broad area of shower and thunderstorm activity. The wave quickly organized, and a low pressure system formed to the south of the Cape Verde Islands on August 13. The convection became slightly less organized on August 14, though by early August 15, the NHC reported that a tropical depression was forming. The system was declared Tropical Depression Three later that day. The newly designated depression continued to intensify, and it was quickly upgraded to Tropical Storm Bill. Numerous rainbands had begun to develop, though the storm lacked deep convection near its center. At this time, Bill was already predicted to become a hurricane. By early on August 16, the storm had developed what NHC forecasters described as a "beautiful" cloud pattern, and environmental conditions favored continued strengthening. Bill intensified to attain Category 1 hurricane status on the Saffir-Simpson Hurricane Scale early on August 17. By late August 17, satellite imagery indicated that an eye feature may have been developing. Bill sustained deep convection and well-established upper-level outflow; it was upgraded to Category 2 status shortly before undergoing an eyewall replacement cycle. Early August 18, the storm had established a very symmetric and well-organized appearance on satellite imagery, and a large, pronounced eye. The storm was moving west-northwestward under the steering currents of a subtropical ridge to the north. Information derived from Hurricane Hunter reports and satellite imagery indicated that the storm had strengthened and reached Category 3 intensity on August 18, making it a major hurricane. Despite some wind shear, Bill was upgraded further to Category 4 intensity on August 19 and reached maximum size with hurricane force winds extending 115 miles (180 kilometers) and tropical storm force winds extending 290 miles (467 kilometers) from the center On August 20, the storm began to weaken, being downgraded to a Category 3, as convection associated with it diminished somewhat. The storm's eyewall also weakened, with a portion of it dissipating later that day. Shear also deteriorated the structure of the storm, with clouds being displaced from the main circulation. However, shortly after, the eye became much better defined and developed several mesovortices, a feature typical of intense hurricanes. On August 21, Bill was downgraded to a Category 2 hurricane as the structure of the storm deteriorated; however, the atmospheric pressure in the eye was 954 mbar (hPa) at that time, equivalent to a strong Category 3 storm. By the morning of August 22, the hurricane completed an eyewall replacement cycle and featured a 55 mi (88 km) wide eye. Later on August 22, the storm weakened to a Category 1 hurricane as Bill tracked over cooler waters. The storm maintained its intensity through August 23 as it retained its cloud-filled eye and tracked at a quick pace to the north-northeast producing waves at La Have Bank Buoy (station 44142) (Lat: 42.50N, Lon: 64.02W) and 16 ft surge on coastlines in New England and Nova Scotia. The storm then made landfall shortly before midnight local time, at Point Rosie, on the Burin Peninsula of Newfoundland as a marginal Category 1 hurricane. Shortly after this it was downgraded to a tropical storm, and then lost tropical characteristics. The remnants of Bill crossed the Atlantic Ocean as an extratropical storm and later impacted the United Kingdom with heavy rain and surf.〔(【引用サイトリンク】 British Isles: Infrared satellite )〕 On August 26, the remnants of Hurricane Bill were absorbed by a larger extratropical cyclone, near the British Isles.〔 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「Hurricane Bill (2009)」の詳細全文を読む スポンサード リンク
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