| Cyclone Gretelle ： ウィキペディア英語版|
Tropical Cyclone Gretelle was a deadly storm that struck southeastern Madagascar in January 1997. The seventh named storm of the 1996–97 South-West Indian Ocean cyclone season, Gretelle developed within the intertropical convergence zone on January 19, and gradually intensified while moving southwestward. On January 22, the storm intensified to tropical cyclone status while passing northwest of Réunion; there, Gretelle produced strong wind gusts and heavy rainfall in mountainous regions. Subsequently, the cyclone strengthened to reach peak 10–minute sustained winds of 140 km/h (85 mph). On January 24, Gretelle made landfall near Farafangana, the first in the region in 41 years. The cyclone weakened while crossing Madagascar, but restrengthened slightly in the Mozambique Channel. Gretelle meandered off the coast of Mozambique, bringing gusty winds that downed trees, but caused little damage. An approaching trough turned the cyclone to the southeast, and Gretelle dissipated on January 31 to the south-southwest of Madagascar.
Damage from Cyclone Gretelle was heaviest near where it made landfall in Madagascar. In several villages, over 90% of the buildings were destroyed, leaving about 80,000 people homeless. Wind gusts at Farafangan reached , which knocked trees onto roads and wrecked about 138,000 tons of crops. Heavy rainfall and high waves flooded coastal regions, in some areas up to deep. Overall damage was estimated at around $50 million, and there 152 deaths. After the storm, there was a coordinated international relief effort to provide food and money to Madagascar.
The intertropical convergence zone spawned a tropical disturbance on January 19, developing a circulation just west of St. Brandon. That day, the Météo-France on Réunion (MFR) classified the system as a tropical disturbance, and the Joint Typhoon Warning Center (JTWC) began monitoring the system as a low-pressure area a day prior. The system intensified into Tropical Storm Gretelle late on January 20, by which time the JTWC gave it the designation Tropical Cyclone 20S. Due to a large ridge centered near Île Amsterdam, the storm tracked generally southwestward toward the Mascarene Islands.〔 Early on January 22, the JTWC upgraded the storm to the equivalent of a minimal hurricane, and later that day, the MFR upgraded Gretelle to tropical cyclone status, or with 10–minute sustained winds of at least 120 km/h (75 mph).〔
Shortly after attaining tropical cyclone status, Gretelle made its closest point of approach to Réunion late on January 22, passing about northwest of the island. Subsequently, the cyclone developed a small eye,〔 and the MFR estimated peak 10–minute winds of 140 km/h (85 mph) at 0000 UTC on January 23. Meanwhile, the JTWC estimated Gretelle continued to intensify to a 1–minute sustained wind peak of 215 km/h (130 mph) at 0600 UTC on January 24, equivalent to a Category 4 hurricane on the Saffir-Simpson scale.〔 Later that day, the cyclone made landfall on southeastern Madagascar near Farafangana near peak intensity.〔 Reports from the United Nations Department of Humanitarian Affairs considered Gretelle the first cyclone to strike the region in 41 years.〔 Gretelle rapidly weakened over land, emerging into the Mozambique Channel as a tropical depression on January 25. Continuing to the southwest, the depression re-intensified into a tropical storm on January 27.〔
After becoming a tropical storm again, Gretelle slowed in the Mozambique Channel. A cold front bypassed the storm to the south, and a building ridge behind it turned Gretelle to a west-northwest drift. Although it approached southeastern Africa on January 28, an advancing trough turned the storm to the southeast.〔 The next day, the JTWC briefly re-upgraded Gretelle to the equivalent of a minimal hurricane, and on January 30, the MFO estimated a secondary 10–minute wind peak of 85 km/h (50 mph). Accelerating to the south-southeast, Gretelle dissipated on January 31 well to the south-southwest of Madagascar.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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