The Northern Tornadoes Project has confirmed storm damage in Parkhill, Ont., on Sunday was due an EF1 tornado as well as a weak downburst while damage in Ailsa Craig was due to an EF1 downburst.
According to the NTP, the EF1 tornado in Parkhill touched down at roughly 9:55 p.m. Sept. 12, with an estimated maximum wind speed of 150 km/h. The tornado tracked across the ground for just under seven kilometres with a path 300 metres wide. At the same time, an EF0 downburst also developed in the area with a maximum wind speed of 115 km/h.
In Ailsa Craig, the NTP says an EF1 downburst hit the region at 10 p.m. Sept. 12, with an estimated maximum wind speed of 150 km/h. Both incidents caused tree and structural damage.
Tornadoes and downbursts both involve damaging winds but their formation and the resulting damage associated with them are different.
David Sills with the Northern Tornadoes Project says in a tornado, winds from the ground converge toward the tornado and move up into the storm causing a long, narrow path of damage. In the simplest terms, the air moves from ground to sky.
In a downburst, however, the air moves from sky to ground. Sills says rain-cooled air descends from the thunderstorm and then spreads out at ground level, generating winds that often diverge instead of converge, creating damage over a wider area.