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The Southern Ontario Tornado Outbreak of 2005 is a series of thunderstorms on the afternoon of August 19, 2005, that spawned tornadoes damaging homes in the Conestoga Lake, Fergus, and Tavistock areas. A tornado was reported within the Toronto city limits, although this was never officially confirmed by the Meteorological Service of Canada. The storms morphed into heavy rain cells when reaching Toronto. The Insurance Bureau of Canada has estimated that insured losses were the highest in the province's history, exceeding 500 million Canadian dollars, two and a half times that of Ontario's losses during the 1998 ice storm and the second largest loss event in Canadian history. == Meteorological events == On the early morning of August 19, a low pressure area was sitting over Northern Michigan with a cold front southwestward. This same system had been causing an outbreak of tornadoes over Wisconsin the day before. As shown in the map to the left, there was up to of precipitable water in the warm air mass invading Southern Ontario with a strong southwesterly low level jet parallel to the cold front and the presence of an upper jet-stream. All of these were very favorable for the development of severe thunderstorms. Furthermore, the wind shear in the lower troposphere was creating a large helicity value conducive to a tornado potential. With the advancing cold front, two lines of thunderstorms developed. The first one was near Stratford, Ontario ( west of Kitchener), and spread as far north as Georgian Bay near Collingwood, Ontario while the second one was following behind near the shores of Lake Huron.〔 They tracked eastward and reached as far as Oshawa during the afternoon.〔 Dozens of storm cells populated the line, two of them developing into tornadic supercells. At their worst, the tornadoes reached the F2 level, with gusts between .〔 Severe thunderstorm warnings were sent, mentioning the possibility of tornadoes in view of the radar output and the potential analysis.〔 The main storm, later dubbed the ''Toronto Supercell'', spawned a first tornado tracking through Milverton () to Conestogo Lake () (west of Elmira) from 12:40 to 1:20 pm local time. A second twister moved from Salem () to Lake Belwood () (north of Guelph), passing just to the north of Fergus 10 minutes later.〔 When the storm came close to the Greater Toronto Area, a tornado warning was issued, but the storm changed its characteristics. It produced winds of well over , golf ball sized hail, but mostly heavy rain flooding many parts of the city between 2 and 4 pm.〔 Finally, another severe storm passing Southeast of Stratford, in the Tavistock area (), gave an F1 tornado with winds between by 3:20 pm.〔 〕 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「Southern Ontario Tornado Outbreak of 2005」の詳細全文を読む スポンサード リンク
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