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Typhoon Paka, known in the Philippines as Typhoon Rubing, was the last tropical cyclone in the 1997 Pacific Ocean hurricane and typhoon season, and was among the strongest Pacific typhoons in the month of December. Paka, which is the Hawaiian name for Pat, developed on November 28 from a trough well to the southwest of Hawaii. The storm tracked generally westward for much of its duration, and on December 7 it crossed into the western Pacific Ocean. Much of its track was characterized by fluctuations in intensity, and on December 10 the cyclone attained typhoon status as it crossed the Marshall Islands. On December 16, Paka struck Guam and Rota with winds of 230 km/h (145 mph), and it strengthened further to reach peak winds on December 18 over open waters. Subsequently, it underwent a steady weakening trend, and on December 23 Paka dissipated. Typhoon Paka first impacted the Marshall Islands, where it dropped heavy rainfall and left in damages. Later, it passed just north of Guam, where strong winds destroyed about 1,500 buildings and damaged 10,000 more; 5,000 people were left homeless, and the island experienced a complete power outage following the typhoon. Damage on the island totaled , which warranted the retirement of its name. Paka also caused minor damage in the Northern Mariana Islands, and overall the typhoon caused no reported fatalities. ==Meteorological history== As the weather synoptics of the northern Pacific Ocean transitioned into a late-fall to early winter-type pattern, convection from the monsoon trough extended to the east of the International Date Line. During late November, a westerly disturbance developed into twin troughs on opposite sides of the equator; the one in the Southern Hemisphere ultimately developed into Tropical Cyclone Pam, while the one in the Northern Hemisphere formed into an area of convection about 2000 km (1240 mi) southwest of Hawaii. The disturbance gradually organized as it drifted north-northeastward, and on November 28 it developed into Tropical Depression Five-C about 465 km (290 mi) west-northwest of Palmyra Atoll. Operationally, the Central Pacific Hurricane Center (CPHC) did not begin issuing warnings on the system until December 2.〔 The tropical depression continued drifting north-northeastward, and failed to strengthen significantly. It turned to the west on December 1, due to the presence of a strong anticyclone to its north with a ridge extending westward past the International Date Line. On December 2, based on satellite estimates, the CPHC upgraded the depression to Tropical Storm Paka while located about 1000 km (625 mi) south-southeast of Johnston Atoll. Due to the presence of high clouds across the area, forecasters had difficulty at times in locating the low-level circulation. After becoming a tropical storm, Paka remained nearly stationary for about two days before resuming a slow motion to the west-southwest. It steadily intensified due to warm water temperatures, and on December 3 the storm attained winds of 105 km/h (65 mph). The next day, however, it encountered dry air and began weakening; by December 6, the winds had decreased to minimal tropical storm status for about 12 hours. Subsequently, Paka began to re-intensify, and on December 7 the storm crossed the International Date Line into the western North Pacific Ocean with winds of 80 km/h (50 mph).〔〔 Upon entering the western North Pacific Ocean, tropical cyclone warning duties transferred from the CPHC to the Japan Meteorological Agency (JMA), and the JMA first assessed Paka as a 65 km (40 mph) storm. The Joint Typhoon Warning Center (JTWC) unofficially assumed warning duties for interests in the United States Department of Defense. Paka continued to intensify after crossing the date line, and from late on December 7 through early the following day it remained a strong tropical storm. However, upper-level wind shear increased, and it again weakened. At 1200 UTC on December 9, the JTWC assessed Paka as an 85 km/h (50 mph) tropical storm and forecast it to continue weakening. By December 10, the shear had begun to decrease as the storm moved through the Marshall Islands, and that night the JTWC upgraded Paka to typhoon status.〔 Paka officially attained typhoon status when JMA classified it with winds of 120 km/h (75 mph) at 0000 UTC on December 11.〔 After attaining typhoon status, Paka strengthened fairly quickly, and by December 12 it reached sustained winds of 150 km/h (90 mph) for a ten-minute (10 min) duration,〔 or 215 km/h (135 mph) over a one-minute (1 min) duration. Subsequently, it briefly weakened as its forward motion increased. However, Paka again re-intensified, and at 1200 UTC on December 14 it attained the unofficial ranking of super typhoon status while over the open Pacific Ocean.〔 At the same time, the JMA classified it with 10 min sustained winds of 175 km/h (110 mph).〔 After reaching its initial peak intensity, Typhoon Paka began to weaken as it approached the southern Mariana Islands; the NEXRAD Doppler weather radar from Guam revealed the presence of a primary eyewall of 74 km (46 mi) in diameter, with a fragmented inner wall cloud of 19 km (11 mi) in diameter.〔 Additionally, satellite imagery indicated an eyewall mesovortex within the eye of the typhoon. It slowed and began to re-intensify as it continued westward, and at 0530 UTC on December 16 the northern portion of the outer eyewall of Paka passed over the island of Rota; 20 minutes later, the southern portion of the inner wall cloud moved across northern Guam.〔 As it tracked through the Rota Channel, the center of Paka passed about 8 km (5 mi) north of the northern tip of Guam, its closest approach to the island.〔 Typhoon Paka continued to steadily intensify after passing the Marianas Islands, and late on December 17 it reached its peak intensity of 185 km/h (115 mph 10 min sustained) while located 440 km (275 mi) west-northwest of Guam.〔 Early on December 18, the JTWC assessed it as attaining peak winds of 295 km/h (185 mph 1 min winds).〔 On December 19, it entered the area of responsibility of the Philippine Atmospheric, Geophysical and Astronomical Services Administration, or PAGASA, and was named Rubing. Shortly thereafter, Paka moved through an area of progressively increasing wind shear, which resulted in a steady weakening trend.〔 By December 21, winds decreased to tropical storm status. The next day, it degenerated into a tropical depression before it dissipated on December 23.〔 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 Paka」の詳細全文を読む スポンサード リンク
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