Implementation and Application of the EF-Scale in Canada

The Enhanced Fujita Scale (EF-Scale) was implemented by Environment Canada on April 1st, 2013, with a number of minor modifications to both suit the Canadian context and address known problems. The wind speed scale was revised - using the original 'expert elicitation' data from Texas Tech University - to ensure that the lower bound of EF0 was approx. 90 km/h, the threshold for operational wind-related warnings in Canada and the threshold at which trees begin to suffer significant damage. For comparison, the lower bound in the United States implementation is approx. 105 km/h. In addition, several damage indicators were added or revised, based on recent research and operational experience. Lastly, a consistent rounding scheme (nearest 5 km/h) was applied to all wind speed values. More than 35 tornadoes ranging from EF0 to EF2 have been rated using the new scale. Experiences with the new scale and details on the modifications will be presented.