|
Typhoon Noul, known in the Philippines as Typhoon Dodong, was a powerful tropical cyclone which impacted Okinawa, Taiwan, the northeast portion of Luzon, and the Caroline Islands in May 2015. The sixth named storm and third typhoon of the annual typhoon season, Noul formed as a tropical depression over the eastern Caroline Islands on May 2, and it was upgraded to a tropical storm late on May 3. After rapid deepening on May 9, Noul became the second-strongest tropical cyclone of the basin in 2015 in terms of windspeeds. Subsequently, increasing vertical wind shear and decreasing water temperatures caused it to start weakening. ==Meteorological history== On April 30, a tropical disturbance formed southwest of Chuuk, and it was recognized as a low-pressure area by the Japan Meteorological Agency (JMA) early on the next day. Due to deep convection consolidating with the low-level circulation center, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert on May 2, shortly before the JMA upgraded system to a tropical depression. Soon, the JMA started to issue tropical cyclone warnings to the system, expecting a tropical storm within 24 hours; additionally, the JTWC also upgraded the system to a tropical depression early on May 3. When the system had formed a compact central dense overcast late on the same day, the JMA upgraded it to a tropical storm and named it ''Noul'', while the JTWC upgraded it to a tropical storm at the same time. Owing to moderate vertical wind shear on May 4, Noul’s low-level circulation center was briefly partial-exposed, and the system itself drifted very slowly under the steering influence of a weak subtropical ridge. Late on May 5, after slowly consolidating, Noul was upgraded to a severe tropical storm by the JMA and a typhoon by the JTWC, when it was located near Yap with an unstable low-level eye revealed by a microwave imagery. Steered by the deep-layered subtropical ridge on May 6, Noul began tracking west-northwestward faster and was upgraded to a typhoon by the JMA at noon. Right after Noul entered the Philippine Area of Responsibility and was assigned the name ''Dodong'' by the PAGASA early on May 7, the typhoon briefly formed a cloud-filled eye but collapsed very quickly. Noul formed a cloud-filled eye again on May 8 but also collapsed quickly. Due to radial outflow, low vertical wind shear and sea surface temperature above 30°C, Noul started rapid deepening on May 9, forming a sharply well-defined 35-km (20-mile) eye embedded in a deepening symmetric core; therefore, the JTWC upgraded it to a super typhoon late on the same day. The JMA declared that Noul reached peak intensity early on May 10, with central pressure at 920 hPa (27.17 inHg) and ten-minute maximum sustained winds at 205 km/h (125 mph), becoming the strongest typhoon in 2015 in terms of sustained winds, although it was surpassed by Typhoon Soudelor in August. The JTWC did the same concurrently, with one-minute maximum sustained winds at 260 km/h (160 mph), equivalent to Category 5 of the Saffir–Simpson hurricane wind scale. Shortly before 17:00 PST (09:00 UTC), Noul made landfall over the town of Santa Ana, Cagayan in the Philippines. Due to land interaction as well as increasing vertical wind shear, Noul began to weaken in the afternoon on May 10 with a cloud-filled eye and warming cloud tops, while the typhoon rounded the southwestern periphery of a deep-layered subtropical ridge and turning poleward. Therefore, the JTWC downgraded Noul to a typhoon late on the same day. Despite the significant weakening trend, Typhoon Noul still maintained a large low-level eyewall structure on May 11 when accelerating northeastward towards Okinawa, Japan, supported by radar fixes. Later, high vertical wind shear caused the low-level circulation center to break apart, and the system started its extratropical transition as it entered the westerlies. After passing through Amami Ōshima early on May 12, the JTWC downgraded Noul to a tropical storm, shortly before the JMA downgraded it to a severe tropical storm. Soon, the JTWC issued the final tropical cyclone warning and declared that Noul had become extratropical, so did the JMA. As a new developing storm-force extratropical low, the system quickly passed through the Kantō region of Japan in the afternoon and arrived at the Pacific Ocean again. However, it quickly weakened to a gale-force low when it was located southeast of Hokkaido. The weak system then started to drift east-northeastward for three days until it was absorbed into its new center immediately after crossing the International Date Line on May 16. 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「Typhoon Noul (2015)」の詳細全文を読む スポンサード リンク
|