First atmospheric river of the fall deluges parts of southern B.C.

British Columbia's South Coast is weathering its first atmospheric river of the fall and the province's Ministry of Emergency Management and Climate Readiness says residents should prepare for increased rainfall and the chance of flooding.

Rainfall warnings cover most of Vancouver Island, as well as the Sunshine Coast, Howe Sound, Whistler and Metro Vancouver, with Environment Canada saying a weather system is pumping moisture from the subtropics directly at the B.C. coast.

More than 200 millimetres of rain could fall along sections of western Vancouver Island, while 80-110 millimetres are forecast across the Howe Sound, Whistler and Sea-to-Sky regions before the storm is expected to ease late Wednesday.

Up to 80 millimetres could drench Metro Vancouver, and the weather office says localized flooding in low-lying areas is possible everywhere the warnings are posted.

The rain-shadow effect will protect much of the Interior from heavy downpours, but a special weather statement covers the West Columbia region of southeast B.C., which could see as much as 50 millimetres of rain by early Thursday.

High streamflow advisories are in effect for Vancouver Island and the inner South Coast, as well as the North and South Thompson and Upper Columbia regions of the Interior, while both the emergency management and forests ministries warn the rain could complicate wildfire recovery in regions such as the Shuswap.

"Following a season of severe drought and wildfire, rainfall on impacted areas can generate high surface water run-off and erosion due to a lack of vegetation, leading to a possibility of localized flooding and landslides," the province's statement says.

WATCH | CBC meteorologist Johanna Wagstaffe explains atmospheric rivers:

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.

It says widespread or severe impacts are not expected as part of the latest atmospheric river system, but officials are urging all residents, no matter where they live, to take steps to prepare for seasonal storms.

A series of atmospheric rivers hit the South Coast and southern Interior on Nov. 14, 2021, bringing two days of intense precipitation that caused the deaths of five people, cut all road and rail links with the rest of the province and Canada, and triggered devastating landslides and floods in communities including Abbotsford, Merritt and Princeton.