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Hurricane Greta–Olivia was one of six Atlantic hurricanes to cross over Central America into the eastern Pacific while remaining a tropical cyclone. The seventh named storm of the 1978 Atlantic hurricane season, Greta formed from a tropical wave just northwest of Trinidad on September 13, and despite being in a climatologically unfavorable area, gradually intensified while moving west-northwestward. On September 16, it became a hurricane south of Jamaica. Two days later, the well-defined eye approached northeastern Honduras but veered to the northwest. After reaching peak winds of 130 mph (215 km/h) that day, Greta weakened while paralleling the northern Honduras coast just offshore. On September 19, it made landfall on Belize near Dangriga and quickly weakened into a tropical depression while crossing Guatemala and southeastern Mexico. After entering the eastern Pacific, the system re-intensified into a hurricane and was renamed Olivia, which weakened before dissipating over Chiapas on September 23. Taking a similar path to Hurricane Fifi four years prior, Greta threatened to reproduce the devastating effects of the catastrophic storm; however, damage and loss of life was significantly less than feared. In Honduras, about 1,200 homes were damaged, about half of which in towns along the coastline. The storm damaged about 75% of the houses on Roatán along the offshore Bay Islands, and there was one death in the country. In the Belize Barrier Reef, Greta downed trees and produced high waves, while on the mainland, there was minimal flooding despite a high storm surge. In Dangriga where it made landfall, the hurricane damaged or destroyed 125 houses and the primary hospital. In Belize City, a tornado flipped over a truck and damaged four houses. Damage in Belize was estimated at $25 million (1978 USD), and there were four deaths. ==Meteorological history== A tropical wave exited the west coast of Africa near Dakar, Senegal on September 7. Moving westward across the Atlantic Ocean, the wave spawned an area of convection three days later, which gradually organized. On September 13, the wave moved through the Windward Islands, producing wind gusts of 50 mph (85 km/h) on Barbados. Later that day, it is estimated the system developed into a tropical depression about 75 mi (120 km) west-northwest of Trinidad, based on ship and land reports. Though located in a climatologically unfavorable area, the depression intensified and continued to develop. A Hurricane Hunters flight on September 14 indicated that the depression intensified into Tropical Storm Greta to the north of the Netherlands Antilles. After becoming a tropical storm, Greta intensified slowly due to a strong trough to the northwest,〔 and with the South American coastline located to the south, the southerly inflow was disrupted. With a ridge to the north along the 30th parallel, the storm moved quickly west-northwestward across the Caribbean. On September 16, Greta intensified into a hurricane about south of Jamaica.〔 Shortly thereafter, the trough to the northwest weakened, which had been preventing the storm's intensification.〔 An increasingly well-defined eye developed while approaching the coast of Honduras as the barometric pressure quickly dropped.〔 Early on September 18, the eyewall passed just offshore Cabo Gracias a Dios, the sparsely populated border between Honduras and Nicaragua〔 The NHC described the eye as having "literally ricocheted off of the protruding northeast coast of Honduras", thus sparing much of the country from the strongest winds. At 0710 UTC on September 18, the Hurricane hunters observed a minimum pressure of just off the northern Honduras coast, which was the basis for the estimated peak intensity of 130 mph (215 km/h). This made it a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale.〔 Despite the proximity to land, Greta initially maintained a well-defined structure. The hurricane continued generally west-northwestward due to the ridge to the north, and initially was expected to enter the Bay of Campeche. After passing through the Bay Islands off northern Honduras,〔 Greta weakened slightly while approaching Belize, and made landfall near Dangriga at 0000 UTC on September 19,〔 with winds of about 110 mph (175 km/h). The calm of the eye was reported for three to five minutes there. Rapidly weakening over land, the hurricane deteriorated to tropical depression status over Guatemala within 12 hours of landfall. A large high pressure area from the Carolinas to the central Gulf of Mexico turned Greta southwestward toward the eastern Pacific Ocean. At 0000 UTC on September 20, the Eastern Pacific Hurricane Center (EPHC) took over responsibility for issuing advisories while Greta was 30 mi (50 km) from the coast. Soon after, the depression emerged over the warm waters of the eastern Pacific and re-intensified. At 0600 UTC, the depression re-attained tropical storm status and was named Olivia by the EPHC, due to the storm entering the Pacific basin. After initially moving to the north, Olivia began executing a slow counterclockwise loop. Based on observations from nearby ships and radar, it is estimated Olivia attained hurricane status early on September 22. While tracking towards the Mexican coastline, the system weakened below hurricane threshold; between 1900 and 2000 UTC, Olivia made landfall about 60 mi (95 km) east of Salina Cruz. Early on September 23, Olivia dissipated over the Mexican state of Chiapas. Hurricane Greta–Olivia was a rare crossover storm from the Atlantic to the Pacific, one of six to maintain tropical cyclone status during the crossing. 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 Greta–Olivia」の詳細全文を読む スポンサード リンク
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