Parts of B.C. under flood watch as atmospheric rivers wash over South Coast

Environment and Climate Change Canada says the South Coast will see periods of heavy rain combined with melting mountain snow from Saturday until Wednesday due to the latest atmospheric river.

It warns of potential flooding, high river levels and landslides in a zone covering Vancouver, Squamish and the Sunshine Coast as well as the Vancouver Island communities of Nanaimo, Port Alberni, Tofino and Campbell River.

Rainfall warnings or special weather statements have been posted for Metro Vancouver, all of Vancouver Island, Howe Sound and the Sunshine Coast, predicting up to 90 millimetres of rain by Saturday night. 

"It looks like the the first system that's going to be intensifying [Saturday] afternoon and tonight," said Philippe-Alain Bergeron, a meteorologist with Environment Canada.

"Precipitation would be tapering off at the end of the night."

Bergeron said while Sunday is likely to be drier, more significant rain is expected to start falling sometime around Monday night into Tuesday.

Forecasts call for up to 300 millimetres of rain on West Vancouver Island and the Coast Mountains, with Howe Sound expecting up to 250 millimetres and the Fraser Valley up to 120 millimetres.

The high amount of rainfall Saturday caused two ski resorts on Metro Vancouver's North Shore, Mount Seymour and Grouse Mountain, to cancel nearly all events for the day. Mount Seymour said they anticipated re-opening as usual on Sunday.

B.C.'s Ministry of Emergency Management and Climate Readiness said in a release late Thursday that the storms may also bring winds that could cause power outages, and the province's River Forecast Centre is monitoring streamflow closely.

Flood watch

Bergeron said the atmospheric river has brought high temperatures, which means freezing levels are as high as 2,000 metres, bringing the possibility of snowmelt adding to rainfall.

The River Forecast Centre has placed all of Vancouver Island, the Howe Sound region, the Sunshine Coast and parts of Metro Vancouver and the Fraser Valley under a flood watch, with high streamflow advisories extending east into the Fraser Canyon and north into the Central Coast.

A flood watch is the second level on the provincial forecast centre's three-tiered warning system. It means that river levels are rising, and flooding in areas adjacent to riverbanks may occur.

Dave Campbell, head of the forecast centre, told CBC News that rain was falling on mountains even at high elevations, with the freezing level as high as 2,500 metres.

"We're seeing quite low snowpack this year, and in some ways that is maybe potentially posing some additional challenges," he said. "The shallow snowpack, there's not a lot of capacity to absorb rain."

Environment Canada meteorologist Armel Castellan said the incoming weather system wasn't likely to bring damage as severe as in 2021.

"We're not anticipating [such] heavy precipitation, partly because of the direction that it's coming from," said Castellan. Campbell said the eye of the storm is likely to be located away from the Fraser Valley, which saw the most severe damage in 2021.

Castellan is still warning residents to stay away from fast-moving rivers and said people with basements prone to flooding should be aware that this "may be one of those times."

Drivers who plan to hit the road this weekend should check the DriveBC website to make sure roads are clear.

Province working with Environment Canada: Eby

Environment Canada has improved its warning systems since the last flooding disaster in B.C., and Premier David Eby says it will be on top of the latest series of atmospheric rivers rolling over the South Coast in the next few days.

Eby says there were justified concerns about failures to communicate the "gravity of the potential threats" ahead of an atmospheric river in November 2021 that triggered massive flooding and mudslides.

But he says the province has been working with Environment Canada to ensure residents get better warnings about extreme weather events, and he understands the agency has changed its approach.