Metro Vancouver rainstorm could cause landslides, warns expert

Landslides in the Lower Mainland are likely on Sunday and into Monday as the latest in a series of storms batters the region.

A rainfall warning was issued early Sunday morning for much of Metro Vancouver, parts of the Sunshine Coast, Howe Sound, and the Fraser Valley.

Up to 150 millimetres of rain is expected from Sunday to Monday morning, according to meteorologists. 

Environment Canada meteorologist Bobby Sekhon said the atmospheric river currently affecting the Lower Mainland is a tropical one. 

"While this is not our first [atmospheric river] of the season, this one is unique because it is a true pineapple express, bringing up moisture from the tropics and Hawaii," said Sekhon. 

Meteorologists are expecting freezing levels to rise on areas of higher elevation like Rogers Pass, which means there could be rainfall on the mountains where snow has already fallen.

"All the highway passes and the Interior ... it has been warming so, it changed to rain for Whistler and it will gradually change to rain in the Interior as freezing levels climb," said Environment Canada meteorologist Philippe-Alain Bergeron.

According to Brent Ward, co-director for the Centre for Natural Hazards Research at Simon Fraser University, landslides can be triggered by rain-saturated ground on a steep slope, and Metro Vancouver has already seen an exceptionally wet fall. 

"With these kinds of rainfall levels and how wet things are already, there will be landslides," he said.

Ward said areas that could potentially be problematic include the North Shore, Coquitlam, and Maple Ridge. He also says the rainfall in combination with melting snow could pose a threat for people who live at higher elevations.

"Most of the time [landslides] are relatively small, they don't affect people but there have been problems in the past."

Trouble on the Coquihalla

Allan Quiring, with Quiring Towing, says he's expecting a treacherous day on the Coquihalla Highway, as Sunday saw a closure in both directions due to mudslides.

Quiring said there has been a spike in incidents over the past week due to rain and snowfall. He said he spent 17 hours pulling close to 25 vehicles and trucks out of ditches this last week.

He said drivers should make sure they have winter tires and prepare for potential accidents by bringing food, water, and a blanket.

"If you're leaving the coastal area and we've got heavy rain ... as you raise that elevation up on the highway, you're going to definitely run into heavy snow," Quiring told CBC News. "You want to make sure your vehicle is prepared."

Quiring said that he has noticed more intense storms in recent years compared to when he started towing in 1988. And he's also noticed a lot of motorists are still driving through the mountains with summer tires, bald tires and excessive speeds.

B.C. laws have required all drivers on the Coquihalla Highway and many other routes to have winter tires since Oct. 1.

Wind and snow to return

As the tropical rainstorm dies down on Monday, Bergeron says strong westerly winds could be expected to hit Metro Vancouver by the afternoon.

"We'll have to deal with strong west winds of 40 km/h and gusting to 60 km/h across Metro Vancouver and maybe a bit stronger even for Richmond," Bergeron told CBC News.

He said snow could also return to the Interior and at higher elevations by the end of the week as temperatures dip slightly lower than average after the rainstorm.

"For a few days it will be cool and dry," he said, "but at the end of the week, especially on Thursday night into Friday, there is snow that we're tracking just south of the border."