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In May 2003, a tropical cyclone officially called ''Very Severe Cyclonic Storm BOB 01'' produced the worst flooding in Sri Lanka in 56 years. The first storm of the 2003 North Indian Ocean cyclone season, it developed over the Bay of Bengal on May 10. Favorable environmental conditions allowed the system to intensify steadily while moving northwestward. The storm reached peak maximum sustained winds of 140 km/h (85 mph) on May 13, making it a very severe cyclonic storm according to the India Meteorological Department (IMD), which is the official Regional Specialized Meteorological Center for the basin. The cyclone drifted north over the central Bay of Bengal, gradually weakening due to heightened wind shear. Turning eastward, the storm deteriorated to a deep depression on May 16 before it curved northeastward and re-intensified into a cyclonic storm. It came ashore in western Myanmar and dissipated over land the following day. In the wake of prolonged precipitation during the first half of May, the cyclone produced torrential rains across southwest Sri Lanka while stationary in the central Bay of Bengal. The storm drew extensive moisture that coalesced in the mountainous portion of the island. A station at Ratnapura recorded of rainfall in 18 hours on May 17, including in one hour. In southwestern Sri Lanka, the rainfall caused flooding and landslides that destroyed 24,750 homes and damaged 32,426 others, displacing about 800,000 people. Overall damage totaled about $135 million (2003 USD), and there were 260 deaths. The cyclone also produced light rainfall in the Andaman and Nicobar Islands of India and along the county's Bay of Bengal. The storm funneled moisture away from the mainland, which possibly contributed to a heat wave that killed 1,900 people, and dropped heavy rainfall in Myanmar. ==Meteorological history== Around May 6, the monsoon trough extended across the southern Bay of Bengal, producing a vast field of thunderstorm activity. A broad low pressure area formed by the next day and remained nearly stationary.〔 Over the next few days, the convection varied in intensity until becoming more organized around the nascent surface low on May 10.〔 At 03:00 UTC on May 10, the India Meteorological Department (IMD) reported the formation of a depression about 535 km (330 mi) west of Banda Aceh, Indonesia. Within nine hours, the depression further intensified into a deep depression.〔 Around the same time, the system was classified as Tropical Cyclone 01B by the Joint Typhoon Warning Center. With warm sea surface temperatures, a formidable anticyclone aloft,〔 and low wind shear, the system continued to mature as it tracked northwestward.〔 Early on May 11, the deep depression strengthened into a cyclonic storm – marked by maximum sustained winds of at least 65 km/h (40 mph) – and later in the day into a severe cyclonic storm.〔 Simultaneously, the system was driven toward the north by a ridge of high pressure to the northeast.〔 At the time, the cyclone was located about east of Sri Lanka. The storm continued to intensify, becoming a very severe cyclonic storm on May 12.〔 That day, the JTWC upgraded Tropical Cyclone 01B to the equivalence of a minimal hurricane with winds of 120 km/h (75 mph).〔 In post-season analysis, however, the agency revised the storm's maximum winds to 110 km/h (70 mph).〔 At 06:00 UTC on May 13, the IMD estimated that the storm attained peak winds of 140 km/h (85 mph). The intensity estimate was based on a satellite-derived Dvorak number of 4.5, limited chiefly by the lack of an eye feature.〔 After peaking in intensity, the storm began weakening due to increasing easterly wind shear from the ridge to the north, displacing the center of circulation from the deepest convection.〔〔 Early on May 14, the IMD downgraded the storm to a severe cyclonic storm.〔 Around this time, steering currents slackened, and the cyclone meandered northward over the central Bay of Bengal. By late on May 14, convection had largely dissipated, with the exception of a small area near the center,〔 and the system weakened to minimal cyclonic storm status. Thunderstorm activity continued to wax and wane as the storm turned to the southeastward, though persistent hostile conditions caused the storm to weaken further to a deep depression on May 16. As the nearby ridge translated eastward, the depression was able to move more steadily to the east and later to the northeast, passing northwest of the Andaman Islands on May 18.〔〔 On the next day, the deep depression re-intensified into a cyclonic storm, reaching a secondary peak with winds of 85 km/h (50 mph).〔〔 At about 10:00 UTC on May 19, the storm made landfall close to Kyaukpyu, Ramree Island, in western Myanmar.〔〔 The storm rapidly weakened into a depression and later degenerated into a low pressure area on May 20,〔 and was no longer discernible on satellite imagery by the next day.〔 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「2003 Sri Lanka cyclone」の詳細全文を読む スポンサード リンク
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