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Severe Tropical Cyclone Joan was an intense tropical cyclone that ravaged areas of Western Australia. Forming out of a tropical low on 30 November 1975, Joan gradually intensified as it tracked towards the west. After attaining Category 5 intensity on 5 December, the storm abruptly began to track southward and accelerated. The following day, the cyclone reached its peak intensity with winds of and a barometric pressure of 915 hPa (mbar; 27.02 inHg). Joan only slightly weakened before making landfall in the vicinity of Mundabullagana. The cyclone rapidly weakened after landfall before dissipating over Western Australia on 12 December. Although no fatalities resulted from Joan, the cyclone caused widespread destruction across areas of Western Australia. In Port Hedland, most of the structures were damaged as a result of the storm. In addition 1,000 homes in the town were damaged or destroyed. Further inland record rainfall caused widespread flooding in many areas, causing many rivers and streams to overflow. Due to the severity of the storm, the name ''Joan'' was retired after the season. ==Meteorological history== Cyclone Joan originated from a large cloud mass that formed northwest of Darwin on 30 November 1975.〔 Due to its possibility of formation, the Australian Bureau of Meteorology began to monitor the system, issuing a tropical cyclone alert on the same day. Tracking southwest, the system gained organization, at which time it received the name ''Joan'' on the next day. As Joan progressed to the southwest, it steadily intensified in favorable conditions, strengthening into a Category 1 tropical cyclone on the Australian tropical cyclone intensity scale on the same day.〔(【引用サイトリンク】url=http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/best_tracks/1976/1976s-bsh/bsh041976.txt )〕 Joan continued to steadily intensify as it moved to the southwest, attaining Category 3 status on 2 December, classifying Joan as a severe tropical cyclone.〔 On 5 December, the cyclone intensified into a Category 5 cyclone, the highest rating on the Australian tropical cyclone intensity scale with winds of .〔 The next day, the forward motion of the storm slowed as it passed to the north of Rowley Shoals before abruptly turning towards the south toward the Australian coast.〔 Joan reached peak intensity on 7 December as it was moving south, with maximum wind speeds of and a minimum barometric pressure of 915 hPa (mbar; 27.02 inHg), based on Dvorak satellite intensity estimates.〔〔(【引用サイトリンク】url=http://www.bom.gov.au/cyclone/history/pdf/joan.pdf )〕 Heading towards the south, Joan made landfall near Mundabullangana, Western Australia late on 7 December with winds of and an estimated pressure of 915 hPa (mbar; 27.02 inHg).〔〔 After making landfall, the cyclone steadily weakened over land as it passed over areas of Western Australia.〔 However, after crossing the Hamersley Range on 8 December, Joan began a phase a rapid weakening, and by the end of the day, its maximum sustained wind was only .〔〔 The system became merged with a broad low pressure area the next day before dissipating on 10 December.〔 However, the Bureau of Meteorology continued to track the storm until 12 December.〔〔 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 Joan」の詳細全文を読む スポンサード リンク
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