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Hurricane Janet was the most powerful tropical cyclone of the 1955 Atlantic hurricane season and one of the strongest Atlantic hurricanes on record. The eleventh tropical storm, ninth hurricane, and fifth major hurricane of the year, Janet formed from a tropical wave east of the Lesser Antilles on September 21. Moving westward across the Caribbean Sea, Janet fluctuated in intensity, but generally strengthened before reaching its peak intensity as a Category 5 hurricane with winds of 175 mph (280 km/h). The intense hurricane later made landfall at that intensity near Chetumal, Mexico on September 28. After weakening over the Yucatán Peninsula, it moved into the Bay of Campeche, where it slightly strengthened before making its final landfall near Veracruz on September 29. Janet quickly weakened over Mexico's mountainous terrain before dissipating on September 30. In its developmental stages, Janet caused $7.8 million in damage to the Lesser Antilles and 189 deaths in the Grenadines and Barbados. While Janet was in the central Caribbean Sea, a reconnaissance aircraft flew into the storm and was lost, with all eleven crew members believed to be perished. This remains the only such loss which has occurred in association with an Atlantic hurricane. A Category 5 upon landfall on the Yucatán Peninsula, Janet caused severe devastation in areas of Quintana Roo and British Honduras. Only five buildings in Chetumal, Mexico remained intact after the storm, and an estimated 500 deaths occurred in the Mexican state of Quintana Roo. At Janet's second landfall near Veracruz, significant river flooding ensued, worsening effects caused by Hurricanes Gladys and Hilda earlier in the month. The floods left thousands of people stranded and killed at least 326 people in the Tampico area, leading to the largest Mexican relief operation ever executed by the United States. Janet's landfall as a Category 5 hurricane on the Yucatán Peninsula was the first recorded instance that a storm of such intensity in the Atlantic made landfall on a continental mainland; prior to Janet, landfalls of Category 5 intensity were only known to have taken place on islands. Janet's minimum barometric pressure, recorded in Chetumal, was at the time the second lowest recorded pressure on land associated with a tropical cyclone in the Atlantic, behind the 1935 Labor Day Hurricane. At least 1,023 deaths were attributed to Hurricane Janet, as well as $65.8 million in damages. The name Janet was later retired from the Atlantic list of tropical cyclone names due to its significance to the scientific research community. ==Meteorological history== A weak tropical disturbance was first reported by the Air France and Iberia airlines east of the Lesser Antilles early on September 21. Although it was speculated that the disturbance originated from a tropical wave near Cape Verde, the Weather Bureau considered the system too weak to be detected due to a lack of reports from the islands.〔 See pp. 321-323.〕 At 1800 UTC on September 21, while it was located 350 mi (565 km) east-southeast of Martinique, the disturbance became sufficiently organized for the Weather Bureau to classify it as Tropical Storm Janet, the tenth named storm of the season.〔 Upon classification, Janet quickly intensified as it moved to the west. On September 22, Janet attained hurricane strength, and proceeded to rapidly intensify as it moved westward across the Windward Islands.〔 By 1200 UTC that day, Janet already attained Category 3 hurricane strength with maximum sustained winds of 120 mph (195 km/h), before stalling in intensification. Shortly after 1700 UTC on September 22, the eye of Janet passed over Barbados. A reconnaissance flight into the hurricane discovered that the Hurricane Janet's eye measured only 20 mi (32 km) in diameter,〔 with gale force winds extending 120 mi (190 km) away from the center of circulation.〔 The flight also reported a minimum barometric pressure of 979 mbar (hPa; 28.91 inHg). After passing between the islands of Grenada and Carriacou in the morning hours of September 23, Janet entered an area of unfavorable conditions in the eastern Caribbean Sea.〔 As a result, the hurricane became disorganized, with winds weakening to 90 mph (145 km/h) by 1200 UTC on September 23.〔 A U.S. Navy reconnaissance plane entered the hurricane early on September 24, reporting a lack of organization, and noting an indiscernible center of circulation with weak rainbands.〔 However, the hurricane began to reintensify in favorable conditions, regaining major hurricane strength by 1200 UTC on September 24 and subsequently Category 4 hurricane intensity by the next day.〔 While trekking across the central Caribbean Sea, Janet was only slightly larger than while it was moving over the Windward Islands, with gale force winds extending 125 mi (200 km) out from the center by September 25.〔 Remaining a Category 4 hurricane as it moved erratically westward across the Caribbean, a reconnaissance flight mission during the night of September 25–26 indicated strong rainbands with frequent lightning strikes and a well-defined eye, evidence that the storm was once again rapidly intensifying.〔 As it neared the Yucatán Peninsula on September 26, Janet began accelerating in forward speed.〔 After the reconnaissance flight ''Snowcloud Five'' was lost while making a penetration into the hurricane's eye, another flight early on September 27 reported a minimum pressure of 938 mbar (hPa; 27.70 inHg), with winds in excess of 115 mph (185 km/h) "by a large and incalculable amount."〔 The hurricane was estimated to have intensified to Category 5 hurricane intensity—the highest rating on the modern day Saffir–Simpson hurricane scale—at 1200 UTC on September 27, while in the western Caribbean Sea. Janet continued to intensify afterwards, eventually reaching its peak intensity with maximum sustained winds of 175 mph (280 km/h), with gale force winds having expanded to at least 250 mi (400 km) away from the center of the hurricane.〔 Janet maintained peak intensity as it passed over the Swan Islands before making landfall in extreme southern Quintana Roo, Mexico, just east of Chetumal, Mexico. In that city, a barometer indicated a minimum barometric pressure of 914 mbar (hPa; 27.00 inHg) in the eye of Janet.〔 At the time, this was the second lowest pressure ever recorded on land in a landfalling Atlantic hurricane, behind the 1935 Labor Day Hurricane,〔 though Janet was later surpassed by hurricanes Dean and Gilbert, which also made landfall on the Yucatán Peninsula as Category 5 hurricanes. Once over land, Janet considerably weakened to a Category 2 hurricane with winds of 105 mph (170 km/h). After crossing the Yucatán Peninsula with a forward speed of 21 mph (34 km/h), the hurricane emerged into the Bay of Campeche by 1600 UTC on September 28.〔 The weakened hurricane marginally intensified as it crossed the Bay of Campeche to a secondary peak intensity of 110 mph (175 km/h) with a minimum central pressure of 950 mbar (hPa; 28.06 inHg). Janet eventually made its final landfall 50 mi (80 km) north of the city of Veracruz by 2200 UTC on September 29 as a Category 2 hurricane. After moving inland, the hurricane became quickly disorganized due to the highly mountainous terrain of Mexico, and as a result the Weather Bureau issued its last advisory on Janet.〔 The weakening system degenerated to tropical storm strength by September 30, and later dissipated over central Mexico by 0600 UTC that day. Janet's remnant circulation contributed to the development of a disturbed area of weather off the western coast of Mexico that would subsequently develop into a tropical storm on October 1.〔 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 Janet」の詳細全文を読む スポンサード リンク
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