Environment Canada working on ranking system for atmospheric rivers, B.C. minister says

Vancouver -

In the wake of the atmospheric river that brought devastating floods and mudslides to B.C. this week, Environment Canada is developing a new ranking system for the weather pattern, according to Deputy Premier and Minister of Public Safety Mike Farnworth.

Farnworth said during an update on the province's flood recovery Saturday that he had spoken with the federal weather agency about the planned system.

"This will help all of us be better prepared for everything from localized flooding and winds to bigger storm events," Farnworth said. "This new approach is based on a system the U.S. is already using."

Atmospheric rivers are long, high plumes of moisture-laden air that can bring hours- or days-long rainfall of varying intensity to the west coast of North America.

The weather pattern is becoming more common due to climate change, and a one-to-five scale developed at the University of California seeks to quantify the intensity of individual atmospheric rivers.

Earlier this week, University of Victoria climatology professor Charles Curry, acting lead at the Pacific Climate Impacts Consortium, told CTV News Environment Canada could use weather information it already collects to implement the scale.

“That information can be directly piped from weather forecasts and other data into an analysis which calculates that category for the amount of water vapour that atmospheric river is packing at that moment," Curry said.

Such a scale could also provide a framework for civic or provincial officials to enact the available Alert Ready system for flooding brought on by intense atmospheric rivers. B.C. remains the only province in Canada that hasn’t used the technology since 2019.

Farnworth did not mention the Alert Ready system during his prepared remarks Saturday. Asked if any additional communication was planned in response to a storm approaching the province's North Coast this weekend, the minister said Environment Canada has issued warnings for that region and is considering advisories on the South Coast, as well.

"As the rain moves south, what I've been advised by Environment Canada, is they're looking at about 20 to 40 millimetres of rain," Farnworth said. "Normally, that would not be an issue in terms of concern, but obviously, given the current saturation that we have seen in the ground, we're following that very closely."

The minister said communication would be "key" in the coming days.

"Obviously, we will be watching and if there are issues and challenges, then resources will be deployed to those areas," Farnworth said. "But the critical piece right now is to have good communication with Environment Canada, so that we're able to - on an hourly basis - understand, you know, the weather and what to expect and if it changes and what will that mean?"

With files from CTV News Vancouver's Penny Daflos