Typhoon Matsa - Meteorological History

Meteorological History

The origin of Typhoon Matsa is traced to the formation of an area of convection about 185 km (115 mi) east of Yap in late July. The convection gradually consolidated over a weak low-level circulation, and at 0300 UTC on July 30 the system was first mentioned in the Joint Typhoon Warning Center (JTWC) Significant Tropical Weather Outlook. Located within an area of moderate wind shear, the system continued to slowly organize, and by 1200 UTC on July 30 it was sufficiently organized for the Japan Meteorological Agency (JMA) to classify it as a weak tropical depression while located about 65 km (40 mi) east of Yap. Shortly thereafter, the JTWC followed suit by issuing a tropical cyclone formation alert. The depression tracked steadily westward, followed by a turn to the northwest on July 31 under the influence of a mid-level ridge to its east. It continued to organize, and at 1200 UTC on July 31 it intensified into Tropical Storm Matsa; the depression was unofficially classified a tropical storm six hours earlier by the JTWC. Additionally, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) named the system Tropical Storm Gorio, due to its location within the administration's area of responsibility.

Tropical Storm Matsa gradually intensified as it tracked steadily northwestward; by late on August 1 it strengthened into a severe tropical storm. Outflow and deep convection to the north remained limited, though the storm was able to intensity further to attain typhoon status on August 2 about 780 km (480 mi) south of Okinawa. Intensification slowed, and late on August 3 Matsa reached a peak intensity of 150 km/h (90 mph) while located 495 km (308 mi) east of the southern tip of Taiwan as reported by the JMA; the JTWC and the National Meteorological Center of China reported the typhoon as strengthening further to attain peak winds of 165 km/h (105 mph) on August 4. Shortly after passing over the Japanese island of Ishigaki, Matsa began to weaken steadily as it approached the coast of China, and made landfall as a minimal typhoon late on August 5 near Yuhuan in the southern region of Zhejiang Province. It crossed the Gulf of Yueqing and 40 minutes after its first landfall it struck Mainland China near Yueqing. It quickly weakened to a tropical storm, and within hours of moving ashore the JTWC issued its last advisory. Matsa turned to the north, weakening to a tropical depression on August 7 shortly before entering the Yellow Sea. The weakening depression continued northward, and became an extratropical cyclone on August 9 after hitting the Liaodong Peninsula.