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Largest single-day tornado outbreak in Ontario, ten years later

Tuesday, August 20th 2019, 3:30 pm - August 20, 2019 marks the tenth anniversary of the largest single-day tornado outbreak in Ontario's history.

More than 10 million Canadians were under tornado watches or warnings on the afternoon and evening of August 20, 2009, as storms dropped a staggering 19 tornadoes on the province. By way of comparison, the province averages about 12 per year.

Four of the tornadoes produced F2-category damage including two that tore through the GTA, hitting Woodbridge and Maple and damaging hundreds of homes. F2 tornado winds are estimated to be between 181 and 253 km/h. (Canada didn't adopt the updated EF-scale until 2013.) An impressive eleven tornadoes were rated F1, the final four F0.

REALFINAL TornadoOutbreak Ontario 20090920

SEE ALSO: Northern Tornadoes Project goes coast to coast for Canadian twisters

A single fatality was reported for the event, associated with the first reported tornado of the day, which hit the town of Durham before ripping through a conservation area.

States of emergency were declared for several of the hardest-hit regions, including Grey County, where more than $30 million in damages was reported. All told, damage associated with the outbreak totalled close to $100 million, making it one of the costliest tornado incidents in Canadian history.

The weather pattern driving this outbreak also stirred up severe weather south of the border. In all, 49 tornadoes touched down between August 19 and 20, stretching from Minneapolis, Minn., to southeastern Ontario. The strongest storm of the outbreak -- an EF-3 -- occurred in central Illinois.


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