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Hurricane Omar was a strong hurricane that took an unusual southwest to northeast track through the eastern Caribbean Sea during October, 2008. Forming out of a tropical disturbance on October 13, Omar initially moved slowly in the eastern Caribbean Sea. By October 15, Omar began to quickly intensify as deep convection developed around the center of circulation. Later that day, an eye developed and the storm began to accelerate to the northeast. Early on October 16, Omar reached its peak intensity with winds of 130 mph (215 km/h) and a barometric pressure of 958 mbar (hPa; 28.29 inHg). Shortly after, the hurricane rapidly weakened to Category 1 intensity. After slightly re-strengthening the next day, Omar weakened to a tropical storm before degenerating into a non-convective low pressure area. The remnants of Omar persisted until October 21 at which time it dissipated to the west of the Azores. Throughout the eastern Caribbean, Omar affected numerous islands, most of which only recorded minor impacts. Large swells and heavy rains impacted the ABC islands. Antigua and Barbuda sustained $54 million in damages, mainly on Antigua as nine homes were destroyed, several others damaged and many farms were inundated by flood waters. One person died in Puerto Rico after suffering a stress-induced cardiac arrest. The United States Virgin Islands also sustained significant damage, costing roughly $6 million. Numerous boats and homes were damaged and over 100 power poles were snapped. Total losses from the storm were estimated at $79 million. ==Meteorological history== On September 30, a well-developed tropical wave moved off the eastern coast of Africa and entered the Atlantic Ocean. Deep convection formed around a prominent mid-level circulation as it moved towards the west. However, the convection diminished on October 2 before entering the Caribbean Sea a week later. Upon entering the Caribbean Sea, shower and thunderstorm activity redeveloped around the low. Continued development followed and the low was designated as Tropical Depression Fifteen at 0600 UTC on October 13 while located about 190 miles (305 kilometres) south of the southeastern tip of the Dominican Republic. The previous steady westward motion that the system took across the Atlantic halted as it entered an area of weak steering currents and significant motion was not expected for another day or two. As the structure of the storm improved, it was upgraded to a tropical storm and the National Hurricane Center (NHC) gave it the name ''Omar''.〔 Located to the southeast of a broad and deep tropospheric trough and to the west of a low to mid-level ridge, Omar took a counter-clockwise turn on October 14. Upon becoming a tropical storm, Omar began to undergo an extended period of rapid intensification as very deep convection developed around the center of circulation.〔 Wind shear around the storm, which was previously inhibiting quick development, weakened, allowing for further strengthening. Later that day, an 11.5 to 17.2 mi (18.5 to 27.7 km) wide eye formed as the storm began to turn towards the northeast due to the trough.〔 With the formation of an eye, the Dvorak technique rendered an intensity of 75 mph (120 km/h), signifying that Omar had intensified into a hurricane. The intensification briefly stalled as the eyewall eroded and the center of the storm became slightly elliptical. However, deep convection persisted and strengthening was forecast as the storm neared Puerto Rico. Shortly after, the eye quickly became well-defined and appeared on visible satellite images, an indication the storm was intensifying. The chances of rapid intensification were good as the storm featured well-developed outflow and prominent banding features.〔 With very warm sea surface temperatures, high ocean heat content, low wind shear, and a moist air mass, Omar quickly reached its peak intensity early on October 16 as a Category 4 hurricane with winds of 130 mph (215 km/h).〔 During the intensification phase, the forward motion of the hurricane increased to 20 mph (32 km/h). Once in the Atlantic Ocean, Omar began to rapidly weaken, with winds decreasing by 50 mph (85 km/h) in 12 hours. Visible satellite images depicted an exposed low-level circulation with convection displaced to the east due to a combination of very high wind shear and dry air. By October 17, most of the deep convection associated with the system dissipated; however, a brief decrease in wind shear allowed Omar to re-strengthen to its secondary peak, with winds of 85 mph (140 km/h). During this phase, convection redeveloped around the center and an eye reformed. Later that day, the trough that caused the rapid northeastern motion bypassed Omar, leading to decreasing movement.〔 A weakening storm, Omar continued towards the northeast due to a mid to upper-level ridge located south of the system and the mid-latitude westerlies to the north. Late on October 17, wind shear increased once more as Omar tracked over waters below . Around 0000 UTC on October 18, Omar weakened to a tropical storm as deep convection associated with it dissipated. Twelve hours later, while still producing tropical storm-force winds, the storm degenerated into a remnant low pressure area. The remnants of Omar persisted until 0600 UTC on October 21 when it dissipated about 805 mi (1,295 km) west of the Azores.〔 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 Omar (2008)」の詳細全文を読む スポンサード リンク
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