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Typhoon Keith was the tenth of a record eleven super typhoons to develop during the unusually intense 1997 Pacific typhoon season. Originating from a near-equatorial trough on October 26, the precursor depression to Keith slowly organized into a tropical storm. After two days of gradual strengthening, the storm underwent a period of rapid intensification on October 30 as winds increased to 195 km/h (120 mph). On November 1, the storm further intensified into a super typhoon and later attained peak winds of 285 km/h (180 mph). The following day, the powerful storm passed between Rota and Tinian in the Northern Mariana Islands. After fluctuating in strength over the following few days, a steady weakening trend established itself by November 5 as the typhoon accelerated towards the northeast. On October 8, Keith transitioned into an extratropical cyclone and was last noted early the following day near the International Dateline. Despite Typhoon Keith's close passage to the islands of Rota and Tinian as a powerful storm, neither island received sustained winds over 160 km/h (105 mph). However, these winds resulted in significant damage across the island chain. More than 800 homes were damaged or destroyed by the storm and losses amounted to $15 million (1997 USD). There were no reports of fatalities in relation to the storm; however, one person was injured. ==Meteorological history== Typhoon Keith originated during the third week of October 1997 from a near-equatorial trough near the Marshall Islands. Along with its Southern Hemisphere twin, convection persisted around a weak low-level circulation, beginning on October 18. Slowly tracking westward, the system remained fairly disorganized before conditions allowed it to develop. By October 26, convection consolidated around the center of circulation and symmetrical outflow became established over the storm. Later that day, the JTWC issued a Tropical Cyclone Formation Alert (TCFA) for the system as they anticipated development into a tropical cyclone. Hours later, the Japan Meteorological Agency (JMA) began monitoring the system as a tropical depression. Despite favorable conditions, the low initially failed to develop further, prompting the issuance of a second TCFA on October 27. Later that day, the JTWC issued their first advisory on the depression, classifying it as 29W.〔 Early on October 28, the depression intensified into a tropical storm, at which time it was named Keith by the JTWC. Tracking west-northwestward in response to a subtropical ridge, the storm slowly intensified at roughly half the rate initially forecast. However, on October 30, the storm suddenly underwent a period of rapid intensification, with sustained winds increasing from 100 km/h (65 mph) to 195 km/h (120 mph) in a 24 hour span. Additionally, the barometric pressure decreased by 43 mbar (hPa; 1.27 inHg) during this time. Throughout the following day, the typhoon continued to intensify, becoming a super typhoon – a storm with winds of at least 240 km/h (150 mph) – late on October 31. Later, the system attained its peak winds of 285 km/h (180 mph) and an estimated pressure of 878 mbar (hPa; 25.93 inHg).〔 According to the JMA, however, Keith's peak ten-minute sustained winds were 205 km/h (125 mph) and the pressure was 910 mbar (hPa; 26.87 inHg).〔 Maintaining super typhoon status, Keith moved through the Northern Mariana Islands between 0600–1200 UTC on November 2 with winds of 260 km/h (160 mph). The center of the typhoon moved between the islands of Rota and Tinian; however, it was discovered that the storm had a very compact field of intense hurricane-force winds, estimated to be 55 km (35 mi) across. After moving through the islands, Keith briefly weakened below super typhoon status on November 3 as the eye became partially obscured due to an eyewall replacement cyclone. However, it re-attained winds of 250 km/h (155 mph) the following day as it began to turn towards the north and later northeast. Once the storm completed its turn, Keith accelerated and steadily weakened as it entered the westerly flow north of the ridge previously steering it westward. Early on October 8, the storm transitioned into an extratropical cyclone as it was downgraded to a tropical storm.〔 The extratropical remnants of Keith were last noted by the JMA on October 9 near the International Dateline.〔 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 Keith」の詳細全文を読む スポンサード リンク
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