Environment Canada has issued a rainfall warning for parts of Metro Vancouver and the Sunshine Coast, saying up to 110 millimetres of rain could fall in the region starting Saturday night.
The warning issued Saturday morning covers the northern and eastern sections of Metro Vancouver, as well as the Sunshine Coast and the Fraser Valley, including Abbotsford.
Rainfall is expected to begin overnight on Saturday and continue until Monday afternoon before tapering off, according to the forecaster.
Environment Canada says significant rainfall amounts will be seen at higher elevations, near the North Shore mountains and the Coquitlam region, while much of Metro Vancouver could see between 60 and 90 mm of rain.
“The heavy rain will continue Sunday and through Sunday night,” said Colin Fong, a meteorologist with Environment Canada.
“And at the same time, this system will bring in enough warm air, especially on Sunday, that any snow falling over the ski slopes, such as the North Shore mountains, will start to transition towards rain.”
Fong says the weather system bringing the rain is an atmospheric river, referring to a large, narrow stream of water vapour that travels through the sky.
“We are calling it an atmospheric river, but it looks to be on the weaker side where it will stall on the South Coast, but only for about a 24-hour period,” he said.
It’s a term that became more widely known after record-setting flooding hit B.C. in November 2021, but as meteorologist Johanna Wagstaffe explains, atmospheric rivers are not new to west coast of North America.
The meteorologist says stronger atmospheric river systems can stick around for up to 36 hours. He adds that the silver lining from the heavy rain is that the system will bring warmer temperatures to the South Coast starting Monday afternoon.
“We’ll experience some dry and very warm temperatures for Tuesday and Wednesday,” he said.
“So in our forecast for the Metro Vancouver region, we can potentially expect temperatures reaching almost as high as 15 C.”
Avalanche risk goes up
Avalanche Canada has issued a special public avalanche warning for the Yoho and Kootenay national parks on the B.C.-Alberta border as the weather system moves in this weekend.
Forecaster Lynnea Baker says the warning is due to persistently weak layers of the snowpack, and people in the backcountry should be prepared for unpredictable conditions.
There is a Special Public Avalanche Warning in effect for Banff, Yoho, Kootenay, and Jasper National Parks, Kananaskis Country, and areas immediately adjacent until the end of the day Monday, March 24. <a href=”https://t.co/tbEdr5sBgD”>pic.twitter.com/tbEdr5sBgD</a>
—@avalancheca
For the South Coast, the avalanche risk was rated as “considerable” on Saturday morning, but Baker says the risk could spike starting Sunday due to the precipitation and elevated temperatures.
“The other thing that we are warning people about is the chance of sun coming out,” she told CBC News. “Even brief periods of sun can rapidly increase avalanche danger, and we can see natural avalanche cycles occur.
“So keeping an eye on what’s going on with cloud cover, if you’re starting to see the sun come out, then making sure you’re backing off those sun-exposed slopes is going to be important.”
