|
Typhoon Nangka was a large and strong tropical cyclone impacting central Japan in July 2015. Nangka started its long-living journey as a tropical disturbance over the Marshall Islands and west of the International Dateline, becoming the eleventh named storm of the annual typhoon season on July 3. It quickly intensified while moving to the west-northwest, attaining typhoon status on July 6. Nangka moved through the Northern Marianas Islands, passing directly over the uninhabited island of Alamagan. Shortly thereafter, the typhoon attained peak winds; the Japan Meteorological Agency (JMA) estimated 10 minute sustained winds of 185 km/h (115 mph), while the unofficial Joint Typhoon Warning Center (JTWC) estimated 1 minute winds of 250 km/h (155 mph), making it a super typhoon. Nangka later weakened as it curved to the north, moving across central Japan on July 16 as a minimal typhoon. The storm weakened soon after, dissipating in the Sea of Japan on July 18. The storm first affected the Marshall Islands, bringing strong winds to the capital Majuro. Half of the city lost power, and several boats were sunk. Minimal effects were reported in the Northern Marianas Islands, and later the storm's flow enhanced the monsoon over the Philippines. Effects were worst in Japan, where heavy rainfall reached in Kamikitayama, Nara Prefecture. Total damage across the Kansai region reached ¥18 billion (US$150 million). Nangka killed two people in Japan, injured 55, and damaged or flooded 220 houses. ==Meteorological history== A tropical disturbance formed east of the Marshall Islands on June 30. Convection of that system remained broad and flaring until July 3, when the Japan Meteorological Agency (JMA) upgraded the low-pressure area to a tropical depression. Shortly after the Joint Typhoon Warning Center (JTWC) also upgraded it to a tropical depression and designated it as ''11W'', the JMA upgraded the system to a tropical storm and named it ''Nangka'' late on the same day. When Nangka was also upgraded to a tropical storm by the JTWC early on July 4, several convective bands were wrapping into the center, limited by dry air to the west however. The system intensified into a severe tropical storm at noon on July 5, with a partially exposed low-level circulation center under moderate vertical wind shear and slightly improving outflow. On July 6, as vertical wind shear diminished and outflow improved, Nangka began rapid deepening and formed an eye, upgraded to a typhoon by both the JTWC and JMA. Tracking west-northwestward along the southwestern periphery of a subtropical ridge, Nangka reached its first peak intensity at noon on July 7 with 10-minute maximum sustained winds of 185 km/h (115 mph), aided by excellent radial outflow enhanced by a TUTT cell to the northwest. Satellite imagery also revealed that a deep core was surrounding a contracting and clear 35 km (25 miles) eye. After its first peak in intensity, Nangka slightly weakened as convection along the west side of the system was restricted due to that TUTT cell with an extending upper-level trough, and the eye became cloud-filled. Decreasing wind shear and increasing water temperatures allowed the intensification trend to resume, and the structure became more symmetric late on July 8 as it moved toward the Northern Marianas Islands. A well-defined inner eye re-developed inside of an outer eyewall. On July 9, the JTWC upgraded Nangka to a super typhoon, estimating peak 1 minute winds of 250 km/h (155 mph). The JMA also assessed a 10 minute peak of 185 km/h (115 mph). At 06:00 UTC on July 9, the eye of Nangka passed over the uninhabited island of Alamagan. The typhoon later weakened while turning more to the west, marred by increased wind shear. The eye became cloud-filled, and no longer visible by July 11, although the organization was sustained by good outflow to the south. However, the convection reorganized the next day and the eye reformed. By that time, Nangka was slowing and nearly stationary as the subtropical ridge receded to the east. On July 13, Typhoon Nangka began moving northward toward Japan through a break in the ridge. The typhoon completed an eyewall replacement cycle, and according to the JTWC attained a secondary peak of 195 km/h (120 mph). The re-intensification was also aided by a decrease in wind shear. This trend was short-lived, as the eye again became cloud-filled while the thunderstorms waned in intensity, due to drier air from the north and west. As the eye became more ragged, the winds continued to decrease. On July 16, Nangka made its first landfall in Japan, striking the island of Shikoku near Muroto, Kōchi at around 14:00 UTC. Later that day, it made its second landfall on the main island of Honshu near Kurashiki, Okayama at 21:00 UTC; around the time of the second landfall, the JMA downgraded the typhoon to a severe tropical storm. The convection greatly weakened as it crossed Honshu into the Sea of Japan. Nangka deteriorated further due to lower water temperatures and the circulation becoming disorganized. Late on July 17, the JMA downgraded Nangka to a tropical depression, and early the next day the JTWC discontinued advisories as the storm was dissipating. The JMA continued tracking the tropical depression through July 18. 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 Nangka (2015)」の詳細全文を読む スポンサード リンク
|