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in dollars) | affected = Edmonton, Strathcona County, Sherwood Park | location = | current advisories = | enhanced = | notes = }} The Edmonton tornado of 1987, an event also known as Black Friday to Edmontonians, was a powerful and devastating tornado that ripped through the eastern part of Edmonton, Alberta, Canada and parts of neighbouring Strathcona County on the afternoon of Friday, July 31, 1987. The tornado remained on the ground for an hour, cutting a swath of destruction long and up to a kilometre (0.6 miles, or 3000 feet) wide in places, and peaking at F4 on the Fujita scale. The tornado killed 27 people, injured more than 300 people, destroyed more than 300 homes, and caused more than $332.27 million CAD ($ in dollars) in property damage at four major disaster sites. The loss of life, injuries and destruction of property made it the worst natural disaster in Alberta's recent history and one of the worst in Canada's history. Weather forecasts issued during the morning and early afternoon of July 31, 1987 for Edmonton revealed a recognition by Environment Canada of a high potential for unusually severe thunderstorms that afternoon. Environment Canada responded swiftly upon receipt of the first report of a tornado touchdown from a resident of Leduc County which is immediately adjacent to Edmonton's southern boundary. At least four other tornadoes were reported that day in central Alberta between Millet and Vegreville.〔(【引用サイトリンク】url=http://www.mb.ec.gc.ca/air/summersevere/edtornado.en.html )〕 == Summary == In the week preceding July 31, a low pressure system sitting over southwestern British Columbia fed warm, humid air into central Alberta. Daytime heating along with near-record dewpoints over Alberta triggered a series of strong thunderstorms that persisted throughout the week. On July 31, a cold front developed over western Alberta, colliding with the warm moist air that persisted over the region. Forecasters recognized the elevated risk for severe weather early in the day.〔(【引用サイトリンク】url=http://apsts.alberta.ca/video/watch/1siliYpDcToEQ0ZE2uDZv8 )〕 Weatheradio broadcasts and interviews with the media stressed "vicious thunderstorms" and "extremely strong and violent thunderstorms".〔 Severe thunderstorms developed rapidly over the foothills early in the day and quickly moved eastward. The first severe weather watches were issued over central Alberta late in the morning and continued early in the afternoon. At 1:40 PM, a severe weather watch was issued for the Edmonton area, including Leduc County, Parkland County, and Strathcona County. The watch was later upgraded to a warning at 2:45 PM as the line of storms approached the area. As the cluster of storms approached the Leduc area, a violent cell rapidly developed ahead of the main line of storms and sharply turned northward. The storm passed east of Leduc, where the first tornado report made by a weather spotter at 2:59 PM. The tornado was on the ground briefly before dissipating. Shortly after 3 PM, the tornado again touched down in the Beaumont area, tossing granaries and farm equipment as it grew in size and strength.〔(【引用サイトリンク】url=http://apsts.alberta.ca/video/watch/3vZ5N8oON652dvyH3Ws0dB )〕 At 3:04 PM, a tornado warning was issued for the city. The tornado moved into the southeast portion of the city as a multiple-vortex tornado, and tracked north along the eastern portions of Mill Woods, causing F2 to F3 damage. The tornado continued northward crossing the Sherwood Park Freeway and eventually hitting the Refinery Row area at F4 intensity. The tornado tossed several large oil tanks, leveled several industrial buildings, and several trailers were picked up and scattered at Laidlaw and Byers Transport.〔(【引用サイトリンク】url=http://datalib.library.ualberta.ca/tornado/ )〕 Grass scouring and windrowing of debris occurred, and damage in that area may have been borderline F5, but was never officially ranked as such.〔http://extremeplanet.me/2012/07/16/some-of-the-most-powerful-tornadoes-outside-the-united-states-canada-france-and-japan/〕 The tornado weakened slightly as it passed over an open area between Baseline Road and the North Saskatchewan River. Still, it maintained F2 to F3 intensity as it tore through eastern parts of Clareview toward 4:00 PM, causing heavy damage to several homes in Kernohan, Bannerman and Fraser neighbourhoods.〔 The tornado persisted as it headed northeast toward the Evergreen Mobile Home Park. There, the tornado completely destroyed nearly 200 mobile homes in the area and killed 12 people and injured numerous others. The tornado dissipated shortly after. 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「Edmonton tornado」の詳細全文を読む スポンサード リンク
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