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Cyclone Yali was one of seven severe tropical cyclones to develop during the 1997–98 South Pacific cyclone season. The system that was too become Yali was first noted as a tropical disturbance, to the northeast of Vanuatu during March 17. Over the next couple of days the system moved towards the south-west and gradually developed further, before it was named Yali during March 19, after it had developed into a tropical cyclone. After it was named Yali re-curved and started moving towards the south-southeast, as the monsoonal flow to the north of the system strengthened. While the system was active, Yali affected Vanuatu and New Caledonia, before the extra-tropical remnants impacted New Zealnd where a man was killed and widespread power outages and damage were reported. ==Meteorological history== The system that was too become Yali was first noted as a tropical disturbance, to the northeast of Vanuatu during March 17, by the United States Joint Typhoon Warning Center. During that day atmospheric convection over the disturbance's low level circulation center became better defined, with the JTWC subsequently issuing a tropical cyclone formation alert on the system later that day. Early the next day the Fiji Meteorological Service's Regional Specialized Meteorological Center in Nadi, Fiji (RSMC Nadi) started to monitor the disturbance as a well defined area of low pressure. Later that day the JTWC initiated advisories and designated the system as Tropical Cyclone 29P, while the system was located about to the north-northwest of Port Vila, the capital of Vanuatu.〔 Over the next day the system moved towards the west-southwest between Vanuatu and the Solomon Islands under the influence of the subtropical ridge of high pressure to the south of the system. RSMC Nadi subsequently reported at around 1800 UTC on March 19, that the system had developed into a category one tropical cyclone on the Australian tropical cyclone intensity scale and named it Yali.〔 After it was named Yali re-curved and started moving towards the south-southeast, as the monsoon flow to the north of the system strengthened.〔〔 Given the fact that Yali was in a region of warm sea surface temperatures and low wind shear, the agency predicted that the storm would intensify to a high-end Category 2 hurricane on the Saffir-Simpson Hurricane Scale. After passing west of Vanuatu, this storm gradually intensified;〔 by March 21, the JTWC reported that Yali had intensified into a Category 1 hurricane.〔 The following day, Nadi estimated that Yali had become a Category 3 cyclone on the Australian intensity scale. Early on March 22, the JTWC reported that Yali had peaked with 1-minute sustained wind speeds of , which made it equivalent to a category 2 hurricane on the Saffir-Simpson hurricane wind scale.〔 At around the same time RSMC Nadi reported that the system had peaked with 10-minute sustained wind speeds of .〔 During that day Yali passed about to the west of the capital city of Vanuatu: Port Villa, before passing over the Vanuatuan islands of Tanna and Aneityum. Shortly after its peak, thunderstorm activity began to decrease, and Yali started weakening. On March 22, the JTWC noted that winds had subsided to tropical storm status〔 while winds soon dropped below Category 2 intensity. At around the same time, a mid-level subtropical ridge began to influence its motion, sending it to the west. As Yali moved to the southwest, the wind field became asymmetric. Based on Nadi data, by March 23, Yali was just east of Noumea, New Caledonia with winds of 50 mph (80 km/h). After passing south of New Caledonia, an upper-level low picked up the cyclone and induced cold air into the atmospheric circulation.〔 Early on March 25, Yali had lost its tropical characteristics as an upper level low captured the system, with cold air working around the northern and western sides of the circulation.〔 However, the JTWC continued to monitor Yali as a tropical cyclone, while the system moved across 160°E and into the Australian region, where they were monitored by the Australian Bureau of Meteorology as an extratropical cyclone.〔 By the next day, Yali's center was less than east-northeast of Brisbane, Australia. Despite a brief revival of convection, on the morning of March 27, the JTWC released its final bulletin on Yali. At this time, the low was located around east-southeast of Brisbane. The remnants of Yali went under a transformation in the Tasman Sea and respectively deepened south of New Zealand.〔 The extratropical remnants of Yali were last noted by TCWC Wellington during March 31, while they were located about to the southeast of Wellington, New Zealand.〔 The remnants were subsequently absorbed into the circumpolar trough. 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 Yali」の詳細全文を読む スポンサード リンク
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