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Toronto Deluged With its All-Time Record 1-Day Rainfall

By: Dr. Jeff Masters, 4:20 PM GMT on July 09, 2013

Torrential rains from a series of "training" thunderstorms that moved over the same location brought Toronto, Canada its heaviest 1-day rainfall in recorded history on Monday, July 8. Toronto's Pearson Airport recorded 126 mm (4.96") of rain, beating Toronto's previous all-time rainiest day record set on October 15, 1954, from the remnants of Hurricane Hazel, when 121.4 mm (4.78") fell. Weather records at the airport go back to 1937. According to meteorologist Rob Davis with the Weather Network, the 97 mm (3.82") that fell in downtown Toronto yesterday was the 2nd greatest 1-day rainfall since 1840. The only greater amount fell on July 27, 1897. Yesterday's storms knocked out power to over 300,000 customers in the city and crippled transportation.

Figure 1. Cars stranded on the #DVP, one of Toronto's busiest highways on Monday, July 8, 2013. Photo posted to Twitter by Michelle Shephard@shephardm.

Figure 2. Radar image taken at the height of Toronto's day of record rain on July 8, 2013, showing a line of heavy thunderstorms to the northwest of the city about to move to the southeast over Toronto, bringing several hours of heavy rain.

Canada has taken a beating from extreme weather this year. Less than a month ago, massive flooding hit the city of Calgary, Alberta, creating a $3 billion flood disaster. This was the most expensive flood in Canadian history, and third most expensive natural disaster of any kind for the country. The only more expensive disasters were a 1989 wildfire ($4.2 billion in 1989 dollars) and a 1977 drought ($3 billion in 1977 dollars.) It's also been a bad fire season in Canada. According to an email I received from Yan Boulanger of Ressources Naturelles Canada, Canadian Forest Service, a fire that has consumed about 500,00 hectares (1,235,000 acres) in Eastmain, Quebec is the biggest fire in Quebec's recent history, from 1959 onward.

Some rather remarkable Toronto flooding photos are posted at the Weather Network.

Jeff Masters


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