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The 1999 Sydney hailstorm was the costliest natural disaster in Australian insurance history, causing extensive damage along the east coast of New South Wales. The storm developed south of Sydney on the afternoon of 14 April 1999 and struck the city's eastern suburbs, including the central business district, later that evening.〔Zillman (1999), 19.〕 The storm dropped an estimated 500,000 tonnes of hailstones in its path.〔Steingold, ''et al.'' (1999), 2.〕〔Henri (1999), 16.〕 Insured damages caused by the storm were over A$1.7 billion,〔Schuster, ''et al.'' (2005), 1.〕 with the total damage bill (including uninsured damages) estimated to be around A$2.3 billion.〔Emergency Management Australia (2006).〕〔Coenraads (2006), 229.〕 It was the costliest in Australian history in insured damages, surpassing the A$1.1 billion in insured damages caused by the 1989 Newcastle earthquake. Lightning also claimed one life during the storm, and the event caused approximately 50 injuries.〔Bureau of Meteorology (2007).〕〔Emergency Management Australia (2003), 61.〕 The storm was classified as a supercell following further analysis of its erratic nature and extreme attributes. During the event, the Bureau of Meteorology was constantly surprised by the frequent changes in direction, as well as the severity of the hail and the duration of the storm. The event was also unique as the time of year and general conditions in the region were not seen as conducive for extreme storm cell formation.〔〔Zillman (1999), 29.〕 ==Conditions and climatology== The conditions around Sydney on 14 April were calm, although a slight instability in atmospheric conditions was recorded by the Bureau of Meteorology in the region. Two instability events had been identified in the greater Sydney area, but both were considered minor by the meteorological agencies. A weak cold front was moving north along the coast, and moderate precipitation was falling over the Blue Mountains, southwest of the city. The meteorological reports and figures, however, suggested that the general atmospheric conditions were "not conducive" to support the formation of a major thunderstorm in the region.〔Whitaker (2005), 99.〕 Historical records show that the formation of severe thunderstorms for the time of day and year had been rare, and it was improbable that they would maintain their intensity and cause significant damage.〔Zillman (1999), i.〕〔Leigh (1999).〕 This long-standing belief contributed to the Bureau of Meteorology's decision not to issue warnings in the early part of the storm's development.〔 The 1999 event was only the second time in recorded history that hail larger than had fallen in the Sydney metropolitan area in the month of April,〔Bureau of Meteorology (1999).〕 and only the fifth hailstorm to strike Sydney during April in the 200 years of meteorological records for the city.〔Collings ''et al.'' (2000).〕 Hailstorms have had a history of significant damage in Australia. Since records on insured losses by the Insurance Disaster Response Organisation began in 1967 three other hailstorms — Sydney in 1986 and 1990, as well as Brisbane in 1985 — feature on the top-ten list of most insured damages caused by a single natural disaster, in addition to the 1999 storm. Hailstorms have caused more than 30% of all insured damages inflicted as a result of natural disasters in Australia during this period, and around three quarters of all hailstorm damage has occurred in New South Wales.〔 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「1999 Sydney hailstorm」の詳細全文を読む スポンサード リンク
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