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The 1990–91 South-West Indian Ocean cyclone season was fairly quiet, although activity began early and the final named storm formed at a record late date. There were seven named storms classified by the Météo-France office (MFR) on Réunion, as well as three depressions; an additional depression was classified by the Joint Typhoon Warning Center (JTWC), an unofficial warning agency. The JTWC tracked storms in both September and October, although neither affected land. In late November, another short-lived depression formed in the northeastern portion of the basin. Activity remained minimal until January, when Tropical Storm Alison formed in the eastern portion of the basin. Later in the month, Cyclone Bella became the strongest storm of the season, reaching 10 minute maximum sustained winds of 155 km/h (100 mph). It passed near the island of Rodrigues, becoming the worst cyclone there in 20 years and killing half of the population of one endangered species. Bella also likely caused a cargo ship to go missing with 36 people on board. Three storms developed in short succession in the second half of February. Cyclone Cynthia developed rapidly in the Mozambique Channel on February 16 and struck western Madagascar, killing 36 people and ruining local rice harvests. A residual trough after Cynthia dissipated spawned Tropical Storm Debra, which looped in the Mozambique Channel. Toward the end of the month, Tropical Storm Elma exited the basin into the adjacent Australian region, only to re-enter the south-west Indian Ocean and dissipate. Long-lived Cyclone Fatima originated in the Australian basin in late March and changed directions before becoming extratropical. On April 2, a tropical depression struck eastern Madagascar, killing 18 people. The final storm, Gritelle, was named on June 10, the latest on record. ==Seasonal summary== ImageSize = width:1000 height:200 PlotArea = top:10 bottom:80 right:20 left:20 Legend = columns:3 left:30 top:58 columnwidth:270 AlignBars = early DateFormat = dd/mm/yyyy Period = from:01/09/1990 till:01/07/1991 TimeAxis = orientation:horizontal ScaleMinor = grid:black unit:month increment:1 start:01/10/1990 Colors = id:canvas value:gray(0.88) id:GP value:red id:TD value:rgb(0.38,0.73,1) legend:Tropical_Depression id:TS value:rgb(0,0.98,0.96) legend:Moderate_Tropical_Storm id:ST value:rgb(0.80,1,1) legend:Severe_Tropical_Storm id:TC value:rgb(1,1,0.80) legend:Tropical_Cyclone id:IT value:rgb(1,0.76,0.25) legend:Intense_Tropical_Cyclone id:VI value:rgb(1,0.38,0.38) legend:Very_Intense_Tropical_Cyclone Backgroundcolors = canvas:canvas BarData = barset:Hurricane bar:Month PlotData= barset:Hurricane width:11 align:left fontsize:S shift:(4,-4) anchor:till from:19/09/1990 till:25/09/1990 color:TD text:"01S (TD)" from:18/10/1990 till:20/10/1990 color:TD text:"02S (TD)" from:30/11/1990 till:06/12/1990 color:TD text:"A2 (TD)" from:08/01/1991 till:18/01/1991 color:ST text:"Alison (STS)" from:18/01/1991 till:04/02/1991 color:TC text:"Bella (TC)" from:16/02/1991 till:19/02/1991 color:TC text:"Cynthia (TC)" barset:break from:22/02/1991 till:04/03/1991 color:ST text:"Debra (STS)" from:26/02/1991 till:05/03/1991 color:ST text:"Elma (STS)" from:21/03/1991 till:01/04/1991 color:TC text:"Fatima (TC)" from:30/03/1991 till:03/04/1991 color:TD text:"G1 (TD)" from:05/06/1991 till:16/06/1991 color:TS text:"Gritelle (MTS)" bar:Month width:5 align:center fontsize:S shift:(0,-20) anchor:middle color:canvas from:01/09/1990 till:01/10/1990 text:September from:01/10/1990 till:01/11/1990 text:October from:01/11/1990 till:01/12/1990 text:November from:01/12/1990 till:01/01/1991 text:December from:01/01/1991 till:01/02/1991 text:January from:01/02/1991 till:01/03/1991 text:February from:01/03/1991 till:01/04/1991 text:March from:01/04/1991 till:01/05/1991 text:April from:01/05/1991 till:01/06/1991 text:May from:01/06/1991 till:01/07/1991 text:June TextData = pos:(569,23) text:"(For further details, please see" pos:(713,23) text:"scales)" During the season, the Météo-France office (MFR) on Réunion island issued warnings in tropical cyclones within the basin. The agency estimated intensity through the Dvorak technique, and warned on tropical cyclones in the region from the coast of Africa to 90° E, south of the equator. Beginning in November 1990, MFR utilized a high resolution picture transmission station in conjunction with its satellite imagery. This allowed for improved Dvorak ratings, allowing for zooming and adjusting the satellite pictures. The Joint Typhoon Warning Center (JTWC), which is a joint United States Navy – United States Air Force task force, also issued tropical cyclone warnings for the southwestern Indian Ocean. In addition to the named storms, the MFR also tracked four tropical depressions, named A1, A2, A3, and G1. In general, the monsoon was weaker than normal within the basin, which provided less flow across the equator to spawn tropical cyclones. As a result, there was a marked decrease in overall activity compared to the 1989–90 season. The MFR issued 198 cyclone bulletins during the season, a 40% decrease over the previous year. Many of the storms formed at the edge of satellite coverage.〔 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「1990–91 South-West Indian Ocean cyclone season」の詳細全文を読む スポンサード リンク
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