According to the Toronto Star, three out of five trees in Ontario have fallen. It also reported that a woman died when her boat sank in the Ottawa River. Details of an additional fatality in Ottawa have not yet been released, Star wrote.
“My thoughts go out to both their family and friends, and I offer my condolences on behalf of all Ontarians.” Ottawa Premier Doug Ford Tweeted Saturday evening.
A number of deaths from high wind events underscore a common theme: those who participate in outdoor activities are particularly at risk for strong winds. The website of the US Storm Prediction Center states that “those who engage in outdoor activities are particularly at risk,” especially in the case of campers or hikers in forest areas, “who are at risk of being injured or killed by falling trees.”
Extensive damage to trees and power infrastructure has also dealt a major blow to electricity distribution in urban corridors. As of Saturday evening, the power outage aggregator PowerOutage.com has listed about 925,000 disruptions in Quebec and Ontario, a huge event for a country of just 38 million citizens. On Sunday morning, PowerOutage.com reported about 700,000 subscribers still in the dark
Emergency workers responded to more than 500 calls on Saturday for damages, including power lines, fires, falling trees and property damage, CTV Ottawa reported.
The storm complex almost certainly qualifies as a dereko or thunderstorm complex that creates extremely strong gusts of wind across a wide swarm. The effects of their violent winds are often comparable to hurricanes. Derechos are fairly common in the lower 48 states but more rare north of the border and rarely affect such densely populated corridors.
Derechos often hit along the northern perimeter of the heat dome, where conditions are ripe for strong thunderstorms. Indeed, very unusual early-season heat swept across eastern North America on Saturday, setting many cities in the eastern United States on record.
This combination of heat with moisture drawn north from the Gulf of Mexico has fueled extreme atmospheric instability or thunderstorms in eastern Canada. The storms erupted as this hot, humid wind combined with a strong cold front moving eastward. This is the same cold front that submerged Denver in temperatures above 50 degrees Celsius in 24 hours and helped give birth to a deadly tornado in Gaylard, Mitchell.
Historically, far-southeastern Canada has seen about one Dereko event every four years, according to the hurricane forecasting center. But Saturday’s incident was unusually much northeast and hit at an unusual time of year; Many historians hit Canadian Dereco in July or August.
Unusual features of Saturday’s Dereko may be representative of the climate change-related trends in setting up such harmful thunderstorms. According to the Storm Forecasting Center’s website, “corridors of the highest Dereko frequency will probably move toward the poles over time” as the high-pressure warm dome expands north under global warming.
