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Severe Tropical Cyclone George was one of the most powerful Australian tropical cyclones on record, attaining a minimum barometric pressure of 902 mbar (hPa; 26.64 inHg). The cyclone formed on 2 March in the Northern Territory's Top End late in February, and intensified when it entered the Joseph Bonaparte Gulf, before crossing the northern coast of the Kimberley. It moved over the Indian Ocean, intensifying to a Category 4 cyclone, and eventually crossed the Pilbara coast just east of Port Hedland at peak intensity. After further analysis from the Bureau of Meteorology Cyclone George was reclassified to Category 5. It caused significant damage to the town of Port Hedland and numerous isolated mining camps around the town. Losses in Northern Territory amounted to at least A$12 million (US$9.5 million). Two people died and more than a dozen others were infected in a melioidosis outbreak following the Northern Territory floods. Insured damage in Western Australia amounted to A$8 million (US$6.2 million), and there were 3 fatalities. ==Meteorological history== Toward the end of February 2007, an area of low pressure began consolidating over the Arafura Sea. By 26 February, the Australian Bureau of Meteorology (BOM) warning centre in Darwin classified the system as a tropical low with its centre situated northwest of Nhulunbuy. Over the following days, the system meandered around the Top End region and showed signs of gradual organization. Initial forecasts depicted the low as moving gradually eastward and becoming a significant cyclone over the Gulf of Carpentaria; however, after approaching Milingimbi Island on 1 March, the system doubled back to the west in response to a subtropical ridge over central Australia.〔〔 Though overland, the cyclone remained well-organized (a typical occurrence for tropical lows over Top End). Deep convection blossomed on 2 March as it approached the Joseph Bonaparte Gulf. Owing to favourable upper-level outflow and decreasing wind shear, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert for the system that day. The agency estimated the formation of a tropical depression, assigning it the identifier ''17S'', by 00:00 UTC (9:30 a.m. ACST) on 3 March while it was still over land. Hours later, the low emerged over the Gulf and acquired gale-force winds while situated south-southeast of Oenpelli.〔 In light of this, the Darwin warning centre initiated advisories on ''Tropical Cyclone George'', marking the first time since Cyclone Fay in 2004 that the Darwin office named a storm.〔 George quickly intensified once offshore, with a very small banding eye of approximately in diameter appearing on SSMI satellite imagery,〔 and gained winds of 95 km/h (60 mph) by 18:00 UTC (3:00 a.m. AWST on 4 March).〔 The system subsequently made landfall in the Kimberley region of Western Australia at that intensity hours later.〔 Substantial structural degradation took place over land, with the eye feature dissipating,〔 and the BOM estimated the system to have briefly weakened to a tropical low before emerging over the extreme eastern Indian Ocean late on 4 March.〔 Once offshore, George regained tropical cyclone strength as it moved steadily west away from Australia. Intensification was slow due a lack of outflow and increased wind shear.〔 Over the following few days, most forecast models indicated that George would gradually turn to the south as it rounded the subtropical ridge and possibly strike areas between Exmouth and Onslow by 9 March. The models continued to indicate this scenario through 6 March, resulting in a high-confidence forecast from the Perth warning centre. However, on 7 March George took an abrupt, nearly 90 degree left turn through a weakness in the ridge and began moving almost due south.〔 This turn caught meteorologists almost entirely off-guard, with only the United Kingdom Met Office ensemble model depicting this scenario. Post-storm reviews of the forecasting failure pointed toward four factors that may have influenced George at the time but were not initialized by the models: the extratropical transition of Cyclone Humba well upstream over the Indian Ocean, a Fujiwhara interaction with Cyclone Jacob to the northwest, the Beta drift effect, and poorly represented monsoonal flow. Of these factors, the monsoonal flow was determined to have been the main cause in the poor track forecast as models did not capture the degree of influence of these winds on the cyclone.〔 This resulted in the forecast track for George having the greatest error of any cyclone in the Western Australian region in at least five years. The average error of at 48 hours was comparable to the average accuracy of forecasts in the 1980s.〔 Coinciding with George's turn south was a notable improvement of environmental factors. Wind shear, previously inhibiting organization, began to decrease while a nearby upper-level low enhanced the system's outflow.〔 The favorable condition allowed for an increase in both strength and size, with both the BOM and JTWC estimating the cyclone to have attained hurricane-force winds by 12:00 UTC (8:00 p.m. AWST) on 7 March.〔〔 By early on 8 March, George featured an area of gale-force winds spanning nearly across, significantly larger than average.〔 A large cloud-filled eye soon developed before a sudden period of rapid intensification ensued.〔〔 During this phase, the cyclone's eye steadily contracted to a minimum diameter of roughly .〔 Between 09:00 and 10:00 UTC (5:00–6:00 p.m. AWST) on 8 March, George passed directly over Bedout Island.〔 As the eyewall moved over the island, a record-breaking ten-minute sustained wind speed of was measured. This marked the highest ten-minute wind measurement officially recorded in Australia. Based on the extreme winds measured on Bedout and additional intensification thereafter, George was estimated to have reached its peak intensity at 12:00 UTC (8:00 p.m. AWST) with winds of 205 km/h (125 mph) and an estimated barometric pressure of 902 mbar (hPa; 26.64 inHg).〔 Automated Dvorak classifications from the Cooperative Institute for Meteorological Satellite Studies at University of Wisconsin–Madison peaked at 6.8, equivalent to a high-end Category 4 on the Saffir–Simpson hurricane wind scale, as the storm moved ashore. At 10 p.m on 8 March, Cyclone George made landfall north-east of Port Hedland. When it made landfall, it was still at its peak intensity.〔 Damaging wind gusts of were recorded at Port Hedland Airport weather station just before 11 p.m.〔 The anemometer failed shortly afterwards.〔 At 00:12 a.m on 9 March, an air pressure reading of was recorded at Port Hedland Airport; this was lowest recorded at the airport during the passage of the cyclone.〔 George weakened slowly while over land and it was downgraded to a Category 3 late on 9 March. The next day, the Tropical Cyclone Warning Centre in Perth issued its final warning for the system. 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 George」の詳細全文を読む スポンサード リンク
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