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Typhoon Agnes produced among the heaviest rains recorded during the 20th century in South Korea, with falling over a two-day span. The storm originated as a tropical depression near Guam on August 25, 1981. Moving along a west-northwest to northwest track, the system gradually strengthened as deep convection organized around it. The depression was assigned the name ''Agnes'' on August 27 following the development of gale-force winds. Further intensification to typhoon-status occurred by August 29. Agnes attained its peak intensity on August 31 over the East China Sea as a Category 2-equivalent on the Saffir–Simpson hurricane wind scale with winds of 175 km/h (110 mph). Subsequent interaction with a mid-latitude trough induced an extratropical transition as the cyclone slowed and turned north. The system had lost most of its tropical characteristics by September 1, with the majority of convection sheared northeast over South Korea and Japan. Agnes later accelerated northeast and completed its transition on September 3. The remnants continued along this course, impacting northern Japan and the Kamchatka Peninsula before last being noted on September 6 near the International Dateline. Throughout the course of Agnes' existence, several countries were affected by torrential rains and typhoon-force winds. Hardest hit was South Korea where record-breaking rains triggered widespread flooding. More than 12,000 structures were damaged or destroyed by the storm and 191,000 acres (77,300 hectares) of farmland was inundated. A total of 113 people lost their lives in the country while damage reached $134 million. Taiwan saw similarly destructive rains which left 32 people dead of missing. A further 14 lives were lost in mainland China where coastal flooding from the typhoon's slow movement coincided with the spring tide, resulting in the greatest storm surge since 1949 along the Yangtze estuary and Hangzhou Bay. Much of Japan saw rains from the storm, though no significant damage or loss of life took place in the country. ==Meteorological history== On August 23, 1981, following several days of tranquil weather, a Tropical Upper Tropospheric Trough (TUTT) began building westward from the International Dateline, near Wake Island. Over the following 36 hours, an expansive area of convection developed southwest of the organizing TUTT. On August 25, surface observations on Guam in the Mariana Islands indicated the presence of a low pressure system. Coinciding with this, the Japan Meteorological Agency (JMA) declared the formation of a tropical depression at 06:00 UTC. Weather reconnaissance missions throughout the day indicated a 1006 mbar (hPa; 29.71 inHg) center west of Guam, prompting the Joint Typhoon Warning Center (JTWC) to issue a Tropical Cyclone Formation Alert. Following improvement in the convective structure, the JTWC began warning on the cyclone as ''Tropical Depression 18W'' at 18:00 UTC, at which time the depression was situated roughly 665 km (415 mi) west-northwest of Guam.〔 Tracking west-northwest and later northwest around the southwestern edge of a subtropical ridge, steady intensification of the cyclone ensued. Early on August 27, a reconnaissance plane measured a central pressure of 994 mbar (hPa; 29.36 inHg) and flight-level winds of , indicating the system had become a tropical storm. In light of this, the JTWC assigned the name ''Agnes'' to the storm.〔 Additionally due to its proximity to the Philippines, the Philippine Atmospheric, Geophysical and Astronomical Services Administration dubbed the system with the local name ''Pining''. Strengthening occurred at a climatological rate, with Agnes attaining typhoon-status on August 29. A large, banding eye-feature developed within the core of Agnes as it approached the Ryukyu Islands of southwestern Japan. The storm passed 170 km (105 mi) south of Okinawa around 06:00 UTC on August 30 and emerged over the East China Sea. Early on August 31, Agnes achieved its peak strength with winds of 175 km/h (110 mph) and an estimated central pressure of 947 mbar (hPa; 27.96 inHg). This ranked it as a Category 2-equivalent on the Saffir–Simpson hurricane wind scale.〔 The JMA estimated the system to have been slightly weaker, with ten-minute sustained winds of 150 km/h (90 mph) and a pressure of 950 mbar (hPa; 28.05 inHg).〔 As the storm moved over the East China Sea on September 1, Agnes began to interact with a mid-latitude trough situated south of South Korea and began a prolonged extratropical transition. Increasing wind shear exposed the center of the typhoon and displaced convection to the north and east. Subsequent slowing of the cyclone's forward speed as it turned northward resulted in an extended period of heavy rain for much of South Korea. The JTWC estimated Agnes to have become predominantly extratropical by the end of September 1, coinciding with the system weakening below typhoon intensity.〔 The JMA, however, maintained the storm as a tropical system as it began moving northwest. The diminishing cyclone moved over the Korea Strait on September 3 and completed its extratropical transition that afternoon. Accelerating over the Sea of Japan, the remnant storm deepened slightly before striking the northern Japanese island of Hokkaido on September 4 with an estimated pressure of 976 mbar (hPa; 28.82 inHg). After moving over the Sea of Okhotsk, Agnes impacted the Kamchatka Peninsula of Russia on September 5. The system then moved over the open waters of the North Pacific and was last noted near the International Dateline on September 6.〔 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 Agnes (1981)」の詳細全文を読む スポンサード リンク
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