Deadly derecho affected nearly half of Canada's population, spawned EF2 tornado

An intense derecho -- a rapidly-moving thunderstorm complex that produces widespread wind damage -- cut power to nearly 1 million households and caused 11 deaths in the Canadian provinces of Ontario and Quebec on Saturday, May 21. Four days later, over 150,000 customers remain without power, and one power company says it was the most damaging event in their history.

The deadly event unleashed wind gusts that reached hurricane force for nearly 12 hours, carving a nearly 800-mile path from southwest to northeast over Canada's most densely populated metropolitan areas, including Toronto, Montreal and Ottawa.

Millions received a warning from Canada's National Public Alerting System, giving them time to find shelter. It was the first mobile phone alert for thunderstorms to go out since new criteria were set in 2021.

AccuWeather Chief Meteorologist Johnathan Porter said the derecho traveled through an area that includes roughly 18 million people, which is nearly 47% of the country's population, according to AccuWeather's data analytics team.

"Saturday's devastating windstorm across southeastern Canada is likely to be remembered as one of the most impactful, if not most impactful, thunderstorm complexes to affect Canada," Porter explained.

As a result of the damage Saturday, officials in the Ontario towns of Uxbridge and Clarence-Rockford declared states of emergency, with the immediate concern being the thousands of residents stranded without power. On Tuesday, Environment Canada confirmed that an EF2 tornado "embedded in the leading edge of the derecho" had struck Uxbridge. That twister was the strongest tornado reported in the country in 2022 so far.

A total of 925,000 customers were left without power in the wake of the destructive weather, with nearly 150,000 homes and businesses still in the dark four days later on Wednesday afternoon. Hydro Ottawa CEO Bryce Conrad said the storm, which downed four huge transmission towers, caused more damage to the utility's infrastructure than tornadoes in 2018 and even surpassed an infamous ice storm from 1998, which caused billions in damage across eastern Canada.

Canada Derecho Transmission Tower

A power transmission tower is shown crumpled to the ground after a derecho knocked it down on May 21, 2022 (Canada Hydro)

While derechos occur from time to time in the country, they are rare. Two notable derecho events in Ontario occurred in July 1995 and May 1998, but both affected smaller population areas.


"In those cases, storms were moving from west to east, or northwest to southeast and, as such, they affected only a portion of this heavily populated corridor of Canada," said Porter.

In contrast, the Saturday derecho moved southwest to northeast along highly populated areas, causing high impacts from the destructive thunderstorms.

Canada Derecho 5/21 Radar Loop

A radar loop shows the line of storms moving from Detroit to Quebec City, Quebec, on Saturday, May 21, 2022.

In Ontario, nine deaths were caused by falling trees, part of the massive damage due to winds that gusted up to 82 mph, according to local reports. All deaths in Ontario were caused directly by the storm or its aftermath, according to the Canadian Broadcasting Corporation. Police reports from the area say the fatalities include a 44-year-old man, a woman in her 70s who was out walking, a 59-year-old man on a golf course, and one person who was killed in their camping trailer.

Additionally, a woman in Quebec died after being caught in a boat that capsized in the midst of the storm. A 61-year-old man from Lakefield, Ontario, was killed due to a falling tree from the storm, Peterborough Police confirmed on Monday.

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