Environment and Climate Change Canada has released its preliminary assessment of the tornado near Didsbury, Alberta on Canada Day and have given it a rating of EF-4.  The tornado had estimated wind speeds of 275 kilometres per hour and was equivalent to the Edmonton tornado in 1987.

Environment Canada says a thunderstorm developed near Sundre, Alberta in the early afternoon on July 1st intensifying as it approached the Didsbury area and was reported as a tornado around 1:45 p.m. south of the community.

The heaviest damage was reported where the tornado crossed highway 2A between Didsbury and Carstairs. It caused damage to 12 homes, of which three were completely destroyed and four were left uninhabitable. The most notable damage occurred at the farm on the west side of Highway 2A. What Environment Canada describes as a well-constructed home was destroyed at that location with all exterior and above-grade interior walls knocked down. The homeowner was in the house at the time and took shelter in the basement.

As well, all homeowners who ECCC representatives spoke to received the tornado warning notification on their mobile devices.  Environment Canada says it allowed them to either seek shelter in their basements or remove themselves from the area by vehicle because they didn’t have access to shelter.  The tornado is estimated at 620 metres wide, 15.3 kilometres long and lasted for 30 minutes.

The following eight tornadoes have occurred in Alberta with a F3 rating or higher:

25 June 1915 F4 near Grassy Lake
30 June 1982 F3 near Rocky Mtn House
8 July 1983 F3 northwest of Lloydminster.
29 June 1984 F3 near Athabasca.
31 July 1987 F4 Edmonton.
29 July 1993 F3 near Holden.
14 July 2000 F3 Pine Lake.
23 July 2000 F3 Marwayne.