Poster Session P9.10 Elie, Manitoba, Canada, June 22, 2007: Canada's first F5 tornado

Wednesday, 29 October 2008
Madison Ballroom (Hilton DeSoto)
Patrick J. McCarthy, MSC, Winnipeg, MB, Canada; and D. Carlsen and J. Slipec

Handout (592.9 kB)

On June 22, 2007, an historic tornadic event occurred at the small town of Elie, Manitoba, Canada. The tornado tracked through the southwestern edge of the community, obliterating 3 homes. The preliminary damage assessment pointed to F5 (EF5) damage. Canada had never officially recorded a tornado of that magnitude so the tornado was conservatively given a preliminary rating of F4. The survey team wanted more time to assess the information.

A number of factors limited some of the damage assessment, including multiple damage sites due to a number significant tornadoes over a two day period. At the Elie damage site, building construction and the exact track and evolution of the tornado were of primary concern. One important question was whether the ground speed of the tornado was unusually slow. Was the resulting damaged intensity due more to a relentless battering by a weaker tornado than by simply one with much stronger wind speeds?

The tornado event was captured by many photos and videos. An assessment of this information could help answer the tornado intensity question. In the weeks following the event, additional on-site work was done to correlate photos and videos to the damage surveyed. This led to additional insights into the event. Finally, using the locations of some videographers, their video, and landmarks in the area, the when and how the homes were destroyed were established. The results demonstrated that the structural failures were quick. The structural assessments indicated that the homes were well-built and well-secured. Together, the evidence confirmed the initial suspicions of the storm damage survey team and the tornado was officially upgraded to F5.

The presentation will summarize the event and examine some of the critical evidence and techniques used to determine the final assessment.

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