CORNWALL – Environment Canada investigators have determined an intense Friday night thunderstorm which raked the Cornwall area produced a microburst and not a tornado.
The weather agency had a colleague on the ground in the Cornwall area the day after the storm where damage was mostly in the northern and eastern area of the city.
“He reported quite a few trees down in the eastern and northern parts of the city. All in the same direction, so it would seem basically it was a microburst event that knocked trees down in the east and north part of Cornwall,” meteorologist Peter Kimbell told Cornwall Newswatch.
Investigators are able to differentiate between a microburst and a tornado because a tornado would have toppled trees in a somewhat circular formation.
Kimbell said there was very heavy rain – 24.6 millimeters (0.96 inches) in less than a half hour – and wind speeds topped 115 kilometers an hour (60 knots). “Maybe even higher that knocked those trees down.”
Residents also reported intense lightning and damage to small outbuildings.
Kimbell concedes there was little warning from Environment Canada about the intense weather, which drew some public criticism.
“We actually did have a risk of thunderstorms in the public forecast but there was not a watch, nor a warning out, until about 8:30 p.m. (Friday) which was pretty close to when the event actually occurred. Unfortunately, we didn’t have a message out with a lot of lead time so that’s unfortunately difficult to forecast when a severe event is going to happen,” Kimbell told CNW.
Microbursts are a natural formation from thunderstorms, which rapidly develop upwards in the sky. “But where you have updrafts you also have compensating downdrafts and they always produce the normal wind gusts that we experience with thunderstorms. But when they are particularly intense and reach damaging wind thresholds we call them microbursts or downbursts and, in this particular case, that seems to be what happened,” Kimbell said.
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Around 3,000 Cornwall Electric customers lost power Friday night due to the storm.
Regional Manager Michael O’Reilly told CNW the damage was concentrated to three areas:
- McConnell Avenue, north of the railway line, to Headline Road: off at 8:30 p.m. and restored around 11 p.m.
- Seventh Street, Cumberland Street, Brookdale Avenue: off at 8:30pm and restored by midnight
- Area bordered by Nick Kaneb Drive, Campbell Street, Second Street and Montreal Road: off at 8:30pm, most back on by 12:45 am and balance of customers on by 7:15 a.m. Saturday
While the microburst caused extensive tree damage, most of the Cornwall Electric infrastructure was unscathed.
“The trouble that we have is, with the winds, trees break and when trees break they come down into the power lines. So we did have some broken wires but we had to clear trees before we could repair line and re-energize,” O’Reilly said.
“The transformer stations were not affected. The equipment in the transformer stations did their job. When they saw a fault out on the line, they cleared the line to make sure it was de-energized,” he added.