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Severe Tropical Cyclone Sina was the only named tropical cyclone to develop within the South Pacific basin during the 1990-91 season.〔 The system was first noted as a shallow depression within the South Pacific Convergence Zone to the west of Wallis Island. Over the next three days the system moved towards the west-northwest, before it was named Sina during November 24, after it had developed into a tropical cyclone. Over the next couple of days the system intensified further and developed an eye feature as it erratically moved towards Fiji. Sina subsequently peaked in intensity during November 26, before the system passed through the Fijian Islands over the next two days as it started to gradually weaken. Sina subsequently passed just to the north of Tongatapu in Tonga during November 29, before it passed about 160 km (100 mi) to the south of Niue and near the Southern Cook Islands during the next day. The system subsequently rapidly weakened and became an extratropical cyclone during December 1, before they were absorbed by an advancing trough of low pressure near 50°S on December 4. The cyclone caused no deaths and over in damages, as it affected Fiji, Tonga, Niue and the Southern Cook Islands. Ahead of the system affecting Fiji, hundreds of people were evacuated from Fiji's outer island resorts to hotels on the mainland. High winds and heavy rain forced the closure of several local airports and the main Nadi International Airport. As Sina moved through the archipelago, the system destroyed or damaged houses and other building structures, while bringing down electric and telephone lines and uprooting trees. The system also washed away a railway bridge on Vanua Levu that was used to take sugar cane to Labasa's mills, leaving growers no choice but to go through the village of Korowiri. However, the workers refused to go into their fields unless they had police protection to go through the village, after Methodists from the local church attacked a group of growers for working on Sundays in defiance of Fiji's Sunday Observance Decree. Within Tonga only minor damage to weak structures, trees, banana plantations, electric and telephone lines was recorded. Within both Niue and the Southern Cook Islands only minor damage to crops and structures was reported. ==Meteorological history== On November 20, the Fiji Meteorological Service's Nadi tropical cyclone warning center (TCWC Nadi) started to monitor a shallow tropical depression that had developed within the South Pacific Convergence Zone to the west of Wallis Island. Over the next two days the system moved towards the west-northwest and the Fijian dependency of Rotuma, before the depression's chances of developing further became good during November 23, as upper outflow over the system became established.〔〔 The United States Joint Typhoon Warning Center (JTWC) subsequently initiated advisories and classified the depression as Tropical Cyclone 03P at 1200 UTC the next day, after atmospheric convection surrounding the system organized further.〔 Later that day at 19:10 UTC, TCWC Nadi named the system Sina after the depression had developed into a category 1 tropical cyclone on the Australian tropical cyclone intensity scale, while it was located about to the northwest of Rotuma.〔 During November 25, the cyclone continued to intensify and developed an eye as it moved erratically towards the west-southwest and performed a small clockwise loop. Early on November 26, TCWC Nadi reported that Sina had become a category 3 severe tropical cyclone.〔〔 At around this time the JTWC reported that Sina had become equivalent to a category one hurricane on the Saffir-Simpson hurricane wind scale (SSHWS). During that day, Sina's eye became very distinct on satellite imagery.〔 As the system intensified and came under the influence of a changeable upper level steering flow which resulted in Sina moving erratically towards the southeast and Fiji.〔 Later that day TCWC Nadi reported that the system had peaked as a category 3 severe tropical cyclone, with 10-minute sustained windspeeds of .〔 The JTWC subsequently reported early the next day that Sina had peaked with 1-minute sustained windspeeds of , which made it equivalent to a category 4 hurricane on the SSHWS.〔 During that day, Sina remained at its peak intensity as it moved towards the east-southeast and started to be observed on the Nadi radar.〔〔〔 Later that day, as the system started to gradually weaken, it passed about to the south of Viti Levu before it passed over the island groups of Vatulele and Moala and the Southern Lau Islands during November 28.〔 During that day the system moved across the 180th meridian, which prompted the JTWC issue their final warning on Sina and pass the responsibility for warning the United States Government to the Naval Western Oceanography Center.〔〔 Early on November 29, Sina weakened into a category two tropical cyclone on the Australian scale just before it passed to the north of Tongatapu in Tonga.〔〔 During that day, as the system moved eastwards towards the Southern Cook Islands and gradually weakened further, the NWOC issued their final advisory on Sina while estimating that it was equivalent to a category one hurricane on the SSHWS.〔〔 Early on November 30, the system passed about to the south of Niue, before it recurved sharply towards the south-southeast later that day as it approached the Southern Cook Islands. The system subsequently started to rapidly weaken under the influence of strong vertical wind shear and cooler sea surface temperatures.〔 TCWC Nadi subsequently passed the primary warning responsibility for Sina to TCWC Wellington as it crossed 25°S, who quickly reported that the system had lost its tropical characteristics and had become an extratropical depression.〔 Over the next couple of days Sina's extratropical remnants maintained a south-eastward track, before it was absorbed by an advancing trough of low pressure near 50°S on December 4.〔 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 Sina」の詳細全文を読む スポンサード リンク
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