Atmospheric river approaching B.C.'s South Coast, Vancouver Island: officials

B.C.'s River Forecast Centre has issued a high streamflow advisory for parts of Vancouver Island and the South Coast due to an incoming atmospheric river.

An atmospheric river is a large, narrow stream of water vapour that travels through the sky.

Areas of the province will be drenched from Friday night through Sunday, according to officials. West Vancouver Island could get 150 to 200 mm of rain and the South Coast Mountains could get 100 to 200 mm. 

The centre says it doesn't know which areas will be hit the hardest. It said runoff and streamflows will likely start to increase Friday night, starting on North Vancouver Island and proceeding south as the storm moves through the region.

WATCH | Heavy rainfall incoming for South Coast: 

Atmospheric river approaching B.C.'s South Coast, Vancouver Island, Environment Canada says

2 days ago

Duration 2:14

Environment Canada has issued a heavy rainfall warning for many parts of the South Coast. An atmospheric river is expected to drench the coast from tonight through Sunday. As Pinki Wong reports, the predicted weather event has some in North Vancouver taking extra steps to prepare.

Significant flooding isn't expected, the centre said, but localized flooding and water pooling on roads are possible, particularly at lower elevations and in areas with poor drainage. 

"Fast-flowing rivers pose increased risk to life safety, and the public is urged to be cautious. The River Forecast Centre continues to monitor the conditions and will provide updates as conditions warrant," the centre said in its advisory.

WATCH | Atmospheric rivers, explained:

What is an atmospheric river?

2 years ago

Duration 1:23

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.

Environment Canada has also issued rainfall warnings for west Vancouver Island and East Vancouver Island. 

It said for regions north of and including Tofino, heavy rain is expected Friday evening and will ease to periods of light rain on Saturday. 

Meteorologist Lisa Erven said heavy snow is expected in the South Coast mountains, which will help replenish B.C.'s low snowpack. A February River Forecast Centre report showed the snowpack at around 72 per cent of normal across the province, following a historically dry January.

But she warned of tricky travel conditions and advised drivers to be prepared for delays.

"Keep an eye on weather alerts, in particular, for the Sea to Sky Highway between Squamish and Whistler, and including the community of Whistler itself," she said.