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Cyclone Olaf was the sixth cyclone to form in the Southwest Pacific Ocean during the 2004-05 South Pacific cyclone season. Olaf was also one of three simultaneous cyclones to form during the 2004-05 season, forming 21 hours after Cyclone Nancy formed to the east. A powerful Category 5 cyclone, Olaf stuck American Samoa causing heavy damage although exact estimates are unknown. Despite the damage, there were no reported deaths or injuries from the cyclone. Olaf was third South Pacific cyclone to hit the Cook Islands during the 2004-05 season (the other two being Meena and Nancy), and Cyclone Percy would later affect the already devastated archipelago less than 2 weeks later. ==Meteorological history== The origins of Olaf were from a broad area of low pressure, that had developed between the island nation of Tuvalu and the Samoan Islands by February 10. This area of low pressure, subsequently spawned two tropical disturbances during February 10. The first disturbance: 09F was located, to the north-northeast of Samoa and later developed into Severe Tropical Cyclone Nancy. The second was designated as Tropical Disturbance 08F by the Fiji Meteorological Service, while it was located about to the northeast of Fiji. A tropical wave formed on February 10. The tropical wave, then spawned two areas of low pressure, one of which became Tropical Depression 08F. At 1300 UTC, the tropical depression was located 490 miles north west of Apia. By 1500, the depression organized into a tropical storm with 40 mph wind and was named Olaf. At the time of formation, the tropical storm was nearly stationary. The low wind shear and warm water temperatures allowed Olaf to undergo rapid intensification. In a 12 hour period, Olaf quickly became a Category 1 cyclone with 80 mph (130 km/h) winds in a 10 minute average speed. On February 15, the barometric pressure fell to 930 mbar as Olaf reached Category 4 status. After reaching Category 4 status, Olaf then moved on a south-southeasterly course at 7 mph (11 km/h).〔(Olaf Report )〕 Cyclone Olaf then tuned east and moving 100 miles (165 km) east of Western Samoa. On February 16, satellite imagery depicted a well-defined eye as Olaf strengthened into a Category 5 cyclone. Olaf reached a peak intensity of 165 mph with a barometric pressure of 915 millibars. It is possible Olaf could have a lower pressure but official track reports have Olaf at 915 mbar. At the time of peak intensity, the center of the storm was only 70 miles (120 km) northeast of American Samoa and 90 miles (145 km) northwest of Pago Pago. At the same time, Cyclone Olaf underwent a minor Fujiwhara effect with Cyclone Nancy before resuming its southeasterly course. Moving at 10 mph (16 km/h), the cyclone maintained Category 5 status as the eye passed 15 miles east of Ta'u, American Samoa. During that time, a weather station reported a 931 barometric pressure reading.〔 On February 18, an approaching upper level trough to the south, and strong wind shear caused Olaf to weaken as the storm rapidly moved southeastward. As Olaf moved into the New Zealand area of responsibility, the main circulation separated from the center and Olaf quickly became extratropical 18 hours later. The extratropical remnants of Olaf, quickly re-intensified into a powerful extratropical storm on February 23. The extratropical storm persisted for two days before dissipating near Pitcairn Island 〔 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「Cyclone Olaf」の詳細全文を読む スポンサード リンク
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