EF2 downburst in Ottawa
An NTP storm survey team investigated damage in southern Ottawa following the May 21 derecho. Analysis of the data reveals that a particularly intense downburst, not a tornado, was responsible for the damage there, with maximum wind speeds reaching 190 km/h (EF2).
A preliminary map of the worst-affected area in Ottawa is shown below (green pin is EF1, yellow pin is EF2).
Intermittent intense damage along a path ~5 km wide continues ENE at least as far as Plantagenet. Additional details on that damage will be forthcoming.