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Hurricane Greta was a large and unusually strong late-season Atlantic hurricane in the 1956 Atlantic hurricane season. Originating from a tropical depression near Jamaica on October 30, the system initially featured non-tropical characteristics as it tracked northward. By November 2, the system began producing gale-force winds around the low pressure area; however, winds near the center of circulation were calm. By November 3, the system intensified into a tropical storm and was named Greta. Quickly strengthening, Greta attained hurricane-intensity on November 4 and by the following morning, the hurricane had rapidly intensified into a Category 4 storm with winds peaking at 140 mph (220 km/h). Shortly after, Greta began to weaken as it tracked over cooler waters. The storm eventually became extratropical on November 7 over the central Atlantic. Although Greta did not directly impact land as a tropical storm or hurricane, it generated large swells that impacted numerous areas. One person was killed in Puerto Rico and coastal damages from the waves amounted to roughly $3.6 million (1956 USD). ==Meteorological history== Hurricane Greta originated out of a tropical disturbance in the Intertropical Convergence Zone near Jamaica on October 30, 1956. A Navy reconnaissance plane recorded sustained winds of 35 mph (55 km/h) and found an area of low pressure. Around this time, the system was classified as a tropical depression. Although a ship near the system discovered a cold-core circulation—a feature of non-tropical cyclones—it was classified as tropical.〔 By October 31, the depression passed near the western edge of Haiti and later crossed the eastern tip of Cuba before entering the Atlantic Ocean. By the afternoon of November 1, the depression had moved through the central Bahamas and turned towards the northeast.〔 By this time, the central pressure of the depression had decreased to 998 mbar (hPa; 29.47 inHg) and gale-force winds were recorded over a large area but not near the center. The system was compared to that of a Kona low, a large-scale subtropical cyclone that forms near Hawaii. Early on November 2, the depression turned northwest in response to an area of high pressure over the central Atlantic.〔 Later that day, the first scientific mission into a hurricane with two planes took place when two research aircraft flew into Greta. During the day, an Air Force B-50 aircraft and NHRP B-47 high altitude jet flew into the storm. The storm executed a counter-clockwise loop, ending on November 3, during which time numerous reconnaissance missions were flown into the system. On November 3, the depression was upgraded to Tropical Storm Greta as the circulation featured tropical characteristics. By this time, the storm had also begun a southeastward track.〔 Continuing to intensify, Greta attained hurricane status on November 4 and later that day it attained Category 2 status on the modern day Saffir–Simpson Hurricane Scale.〔〔The Saffir–Simpson Hurricane Scale was not created until 1971; storms prior to that year were called tropical storms or hurricanes〕 After reaching this intensity, the hurricane turned northeastward and accelerated. Rapid intensification took place shortly after, fueled by favorable mid-latitude conditions.〔 On November 5, Greta attained Category 4 status, with winds peaking at 140 mph (220 km/h), making it the strongest storm of the 1956 season.〔 A reconnaissance mission around this time recorded a minimum pressure of 970 mbar (hPa; 28.64 inHg).〔 Around the time of peak intensity, Greta was an extraordinarily large hurricane, with the gale-diameter of the storm extending roughly 1,200 mi (1,930 km).〔 〕 After attaining its peak intensity, the storm began to move over cooler waters, resulting in the circulation becoming elongated.〔 Early on November 6, Greta weakened to a Category 3 hurricane and continued accelerating to the east-northeast. Several hours later, the system weakened to a Category 1 hurricane and by November 7, Greta transitioned into an extratropical cyclone over the central Atlantic.〔 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 (1956)」の詳細全文を読む スポンサード リンク
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