Heavy rain and t-storms expected in Toronto on Tuesday renew flooding concerns

A low-pressure system in southern Ontario is expected to bring heavy rain to Toronto, once again elevating flooding concerns on some of the highest-risk roadways.

Potentially strong thunderstorms are forecasted to begin in Toronto around 11 a.m. on Tuesday, with moderate to heavy rain falling from noon through much of the afternoon. Timing-wise, it could significantly impact the evening commute, with the thunderstorm risk continuing for much of the night.

Toronto could see 5 to 10 mm of rain accumulate through the afternoon and an additional 2 to 4 mm in the evening. The heavy rain will likely prompt weather and potentially flood warnings in Toronto and across much of the Greater Toronto Area (GTA).

Other GTA cities, like Mississauga and Brampton, could see slightly more rainfall accumulation in the evening hours.

Toronto likely to break July rainfall record

With August right around the corner, Toronto is sure to record its rainiest month.

According to the Weather Network, less than 6 mm of rainfall is needed at Toronto Pearson International Airport to bring the monthly total higher than October 1954, when 213.8 mm of precipitation fell due to remnants of Hurricane Hazel.

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With upwards of 20 to 25 mm of rain possible in Toronto on Tuesday, roadways such as Lakeshore Boulevard and the Don Valley Parkway (DVP) are at the highest risk of flooding, as they have been on multiple occasions this month.

More recently, lanes on both the DVP and Lakeshore Boulevard were flooded on July 24 but were passable again shortly after once water levels subsided. It came after Toronto was hit with nearly 100 mm of rain and widespread flooding on July 16.

Cars were stranded for hours on the DVP, commuters waded through inundated transit stations, and residents pumped out flooded basements.

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