Environment Canada issues heavy rainfall warning for southern Ontario

A wet and windy night is expected across our area with Environment Canada issuing a heavy rainfall warning.

We could see rising water levels and slick roads across the province over the next 24 hours.

Environment Canada warns 20 to 40 millimetres of rain could fall within just six hours, with heavier downpours for some.

That rain is expected to come quickly – and that’s where the risk lies.

“This is why it adds a lot of risk to the flooding and standing water everywhere you look. Doesn’t matter how much precipitation we’ve had in the wintertime, April is always the mud season, the flood season,” said David Phillips, senior climatologist with Environment Canada.

The system responsible is what’s known as a Colorado low. And according to Phillips, this one is a classic.

“The key thing about the Colorado low, unlike the Alberta clipper, very similar kind of situations, an Alberta clipper is sort of a hit and run. The Colorado low, though, is picking up moisture from the Gulf of Mexico. So when it enters Ontario, it’s usually a moist system. We’re going to see a good amount of rain,” said Phillips.

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A flood outlook message warns all shorelines, rivers and streams around the GTHA could become dangerous as water levels rise rapidly. Officials are urging residents to stay back from the edges.

The system is expected to hit its peak this evening, with wind gusts possibly reaching up to 50 kilometres an hour, making for a blustery, rain-soaked night.

This yellow rain warning follows a very warm Friday with temperatures well over 20 C.

“That is exactly what April’s about. You can’t figure it out. I mean, it’s like summery-like and wintery-like. And sometimes it’s just an hour between some of those conditions. So it’s almost as if it’s the month that you have to be prepared for almost anything,” said Phillips.

Phillips notes some areas could see 40 millimetres of rain in six hours – close to half of what April normally brings all month long.

“In April, you might get about 55 millimetres of rain for the whole month. So to get 40 millimetres in less than, like, six hours, that’s a lot, especially when we’ve had so much in March,” said Phillips.

The rain will taper off into showers by Sunday, but much colder temperatures and even a few flurries could be on the way.

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