'Potent and impactful storm' on the way to B.C.'s South Coast, Vancouver Island

Heavy rainfall is in store for much of southern B.C. starting Monday, when a “potent and impactful storm” is forecast to make landfall, according to Environment and Climate Change Canada.

A special weather statement issued Sunday morning covers Metro Vancouver, the Fraser Valley, Howe Sound, Whistler, the Sea to Sky Highway, West Vancouver Island, Inland Vancouver Island and the Sunshine Coast.

The statement was upgraded to a rainfall warning Sunday afternoon.

The weather agency says an atmospheric river will bring “very heavy rainfall” and snow at higher elevations Monday and Tuesday as the storm moves across southern B.C.

The coming precipitation will increase the risk of flooding and landslides, ECCC warns.

However, the statement notes that the storm is expected to be “much weaker in comparison” to the atmospheric river event of November 2021, which triggered catastrophic flooding and widespread infrastructure damage.

Still, ECCC meteorologist Louis Kohanyi urges people not to take the latest warnings lightly.

"There could be potentially some flash floods,” he said. “For people who are driving, there could be water pooling on roads. And also localized flooding in low-lying areas."

On Sunday, 20 to 50 millimetres of rain is forecast to fall across southern B.C., according to the River Forecast Centre. The rain will intensify on Monday, bringing an estimated 150 to 250 millimetres to Western Vancouver Island and coastal mountains over the two day event.

The centre says in Metro Vancouver, the Fraser Valley (up to Chilliwack), Howe Sound and Inland Vancouver Island, the rainfall will total between 60 and 100 millimetres.

Rainfall totals in the Fraser Valley (up to Hope) and the Coquihalla Summit are estimated at 40 to 100 millimetres.

A high streamflow advisory is in effect for the South Coast and Vancouver Island.

The center says river levels are expected to rise quickly starting Monday, and that flows will likely peak Tuesday and into Wednesday. It forecasts minor flooding in low-lying areas.

In an interview Sunday, Jim Loree of North Shore Rescue said anyone who goes hiking over the next several days should be cautious around streams and rivers.

“If people are hiking in on a trail and have to cross a stream and they have to come back the same way, they should expect that those streams could rise,” Loree said. “They might not be able to get back across."

He also said it’s important for people to carry flashlights or head lamps at this time of year because if their return is delayed for any reason, they could find themselves trying to navigate trails in the dark because the sun sets so early.

Despite the warnings, Loree also urged anyone who does find themselves in trouble in the wilderness to call for help as soon as possible so search and rescue volunteers can help them before the situation gets worse.

An elevated ocean water level statement is also in effect for areas of Metro Vancouver, the southern Gulf Islands and the Saanich Peninsula.

The weather agency says “low barometric pressure will combine with a period of high atmospheric tide,” resulting in elevated water levels Sunday. “Minor coastal flooding is possible along exposed shorelines,” it adds.

The highest risk of flooding will be on Sunday, but the elevated water levels will stick around on Monday and Tuesday, according to ECCC.