Atmospheric rivers roll over B.C., melting snow and triggering flood advisories

Vancouver -

Rainfall and flood advisories remain in effect for parts of Metro Vancouver and the Sea to Sky region as balmy weather brings a series of rainstorms to British Columbia's South Coast, melting any sign of heavy snowfall earlier this month.

Environment Canada says a series of atmospheric rivers is rolling over the area through Wednesday, bringing temperatures five to 10 degrees above normal.

A rainfall warning spanning parts of Metro Vancouver and Howe Sound says the warmer airmass will raise the freezing elevation to near 2,500 metres, and snow melting in the mountains could carry the potential for flooding downstream.

A special weather statement, meanwhile, says communities throughout Vancouver Island will also see heavy rain, bringing the potential for localized flooding and the risk of landslides in vulnerable areas, such as those burned in recent wildfires.

“An atmospheric river is a long stretch of moisture, about 1,000 kilometres long and 300 to 400 kilometres wide,” according to Ryan Voutilainen, a storm chaser from Vancouver.

“This is actually a series of atmospheric rivers.”

Grouse Mountain Regional Park closed on Saturday due to hazardous trail conditions. 

B.C.'s River Forecast Centre says the heaviest rainfall will hit western Vancouver Island and the Coast Mountains, with between 200 and 300 millimetres expected in the coming days.

"It's going to be some soggy skiing for the next few days anyways,” said Voutilainen, who says the temperature is too warm for the precipatiation to turn to snow.

Flood watches have been issued by the River Forecast Centre for all of Vancouver Island and much of the South Coast, while lower-level streamflow advisories are in effect for the Central Coast and the Lower Fraser region.

It says forecasts suggest the strongest atmospheric river will arrive on Monday.

BC Hydro has moved reservoir levels down around the Puntledge and Campbell River systems to make way for the massive amount of rain in its resevoirs.

"With the increased precipitation, we know that water levels can rise really quickly and flows can change pretty dramatically, our message to the public is to just stay away from those waterways right now,” said Mora Scott, a BC Hydro spokesperson.

Scott says January has been a dryer month for Vancouver Island, which means reservoirs are in good shape to handle the massive amount of rain.

Environment Canada meteorologist Armel Castellan says it will be very wet, but the storms won't be as bad as the record-breaking floods of November 2021 that washed away bridges, swamped farmland and spurred landslides that killed five people.

With files from CTV News Vancouver's Abigail Turner

This report by The Canadian Press was first published Jan. 27, 2024.