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Very Intense Tropical Cyclone Hellen of March 2014 was one of the most powerful tropical cyclones in the Mozambique Channel on record, as well as the second most intense of the 2013–14 South-West Indian Ocean cyclone season. It formed on March 27 in the northern portion of the channel, and in its formative stages brought rainfall to coastal Mozambique. While moving southeastward, it developed an organized area of convection over the center. Warm waters allowed Hellen to rapidly intensify while passing south of the Comoros, with a well-defined eye forming in the middle of the thunderstorms. The cyclone attained peak intensity March 30, with maximum sustained winds estimated 230 km/h (145 mph) according to the Regional Specialized Meteorological Center, Météo-France in La Réunion. Subsequently, Hellen weakened quickly due to dry air and interaction with Madagascar, and the eye dissipated. On March 31, the storm made landfall in northwestern Madagascar as a weakened cyclone, despite previous forecasts for the center to remain over water. By April 1, Hellen was no longer a tropical cyclone after most of the convection dissipated. The remnants turned to the west, moving over Mozambique without redeveloping. Early in its duration, Hellen's rainfall in Mozambique destroyed hundreds of houses and a bridge. Flooding killed four people in the country, three of whom due to a home collapsing. Later, the cyclone passed south of the Comoros islands, causing flooding due to high storm surge and waves that killed one person. The storm forced 8,956 people to evacuate their homes due to the threat for landslides, while 901 houses were damaged or destroyed. On nearby Mayotte, high rainfall flooded rivers, sweeping one car away. In northwestern Madagascar, Hellen damaged or destroyed 611 houses, leaving 1,736 people homeless. The storm killed three people after capsizing a boat. ==Meteorological history== On March 25, 2014, a weak area of low pressure accompanied by broad, flaring convection became increasingly organized over Mozambique. Owing to favorable environmental conditions, featuring low wind shear, vorticity became more enhanced and symmetrical. A compact system, the low steadily organized as it emerged over the Mozambique Channel on March 26. Though continued land interaction initially hindered development, enhanced outflow supported convective development as it straddled the Mozambique–Tanzania border. With high sea surface temperatures in the storm's track, the JTWC anticipated further organization and issued a Tropical Cyclone Formation Alert at 2000 UTC on March 26. Once further offshore on March 27, the Regional Specialized Meteorological Center Météo-France in La Réunion classified the system as ''Disturbance 14''. Drifting slowly east, a prominent feeder band developed along the system's eastern side; however, this band disrupted low-level inflow of warm, moist air and suppressed convection over the circulation center. Though convection later began to consolidate into a small central dense overcast (CDO) feature by March 28, continued disruption of the low-level inflow prevented much development. Météo-France noted that despite forecasting the storm to peak as a moderate tropical storm, with winds of 75 km/h (45 mph), there was potential for rapid intensification due to the storm's small size. Conversely, the JTWC noted that proximity to land and dry mid-level air, represented by surface outflow boundaries, could hamper significant development. Once further over the Mozambique Channel, the system became increasingly organized and the JTWC initiated advisories on the storm as ''Tropical Cyclone 21S''. Météo-France followed suit at 0000 UTC on March 29 and classified the cyclone as a moderate tropical storm, with the tropical cyclone warning center in Madagascar assigning the name ''Hellen''. Hellen soon assumed an east-southeast track toward Madagascar as a ridge established itself to the northeast. Throughout March 29, the storm became increasingly organized with an eye apparent on microwave satellite imagery. Rapid to explosive intensification ensued during the later half of March 29 into March 30 at a rate Météo-France later referred to as "astounding".〔 Deep convective banding wrapped around a ragged eye, which soon contracted to "pinhole" size. This prompted Météo-France to upgrade Hellen to a tropical cyclone with winds estimated at 150 km/h (90 mph) at 0000 UTC on March 30. Six hours later, they further upgraded the storm to an intense tropical cyclone with winds of 195 km/h (120 mph). Hellen attained its peak intensity between 1100 and 1500 UTC as a very intense tropical cyclone, with winds of 230 km/h (145 mph) and a barometric pressure of 925 mbar (hPa; 27.32 inHg). This ranked it as one of the most powerful storms over the Mozambique Channel on record.〔 The storm featured a 20 km (12 mi) wide eye embedded within a symmetrical and intense CDO, spanning 240 km (150 mi) across. The JTWC estimated Hellen to have attained one-minute sustained winds of 250 km/h (155 mph), making it a high-end Category 4-equivalent cyclone on the Saffir–Simpson hurricane wind scale, although this was lowered to 240 km/h (150 mph) in reanalysis. After peak intensity, the cyclone's eye soon began to fill and cool as weakening ensued. Defying previous forecasts, Hellen continued on a southeasterly track toward Madagascar and the likelihood of it making landfall became apparent. By the end of March 30, Hellen's eye had collapsed and disappeared from satellite imagery, as the combination of dry air and land interaction took their toll on the storm. At about 0800 UTC on March 31, Hellen made landfall on northwestern Madagascar, and the previously unfavorable conditions coupled with land interaction to induce rapid weakening. The ridge to the east turned Hellen to a southwest drift over land. By early on April 1, the convection largely dissipated as the center became difficult to locate, with peak winds dropping to 45 km/h (30 mph). As a result, Météo-France discontinued advisories that day, as did the JTWC. The remnants moved back over open waters, but were not expected to reorganize due to the poor nature of the convection. As the low continued to the west, the convection increased on April 4 while approaching the coastline of Mozambique, although the system failed to redevelop before moving onshore. 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「Cyclone Hellen」の詳細全文を読む スポンサード リンク
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