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Anticipated La Nina wet weather pattern could ease drought conditions in B.C.

Stanley Park,

People use umbrellas while walking along the Stanley Park seawall as rain falls while a small amount of snow remains from a previous snowfall in Vancouver, on Sunday, Dec. 25, 2022. File photo by The Canadian Press/Darryl Dyck

British Columbia's nagging drought could be eased by an incoming weather pattern that may bring a colder and wetter than normal winter, says Sean Fleming, an adjunct UBC professor of atmospheric sciences. 

The prolonged drought has caused wildfires to burn year-round, forced some communities to ration water supplies and dangerously lowered water levels in rivers, impacting salmon runs. 

Citing the U.S. National Oceanic and Atmospheric Administration, Fleming, who works in UBC's Department of Earth, Ocean and Atmospheric Sciences, said early projections show a 71 per cent chance that an La Nina weather pattern will move in. 

La Nina is a climate phenomenon resulting from the flow of warmer water in the Pacific Ocean that typically brings lower temperatures and higher precipitation.

If those projections are accurate, Fleming said that could help to "undo some of the persistent drought conditions."

"Potentially, we could be looking at greater than average flooding this winter if the La Nina conditions pan out," he said in an interview. "That also means, though, greater water supply, greater snowpack in general, greater water supply availability for the next spring and summer."

It could also bring higher power generation potential, he said, as well as stormier weather that might bring down power lines.

BC Hydro spokeswoman Susie Rieder said the power authority is urging people to be prepared for weather-related power outages ahead of storm season, as the multi-year drought has caused trees to weaken. 

"Our meteorologist has been warning that, while drought levels have improved compared to last year, there's still that elevated risk of power outages in the event of a windstorm this fall," she said in an interview.

Rieder said that's mostly true for Vancouver Island and in northern B.C., which had several major wildfires this season. 

"For places like the Lower Mainland and the southern Interior, drought stress has been a bit less, but trees and other vegetation are still at risk compared to a year with average precipitation," she added.

The BC Wildfire Service dashboard shows about 180 wildfires are still burning across B.C. A total of 19 blazes are listed as burning out of control. All but one are burning in the Prince George Fire Centre region.

The latest available data from the province's drought information portal shows that, as of last Thursday, B.C.'s northeastern corner remains at drought Level 5, the highest possible ranking on the scale.

The River Forecast Centre and the BC Wildfire Service declined to comment on current conditions ahead of the provincial election, saying all communication will be "limited to critical health and public safety information, as well as statutory requirements."

Fleming said scientists can often forecast weather about two weeks in advance and predict long-term changes in climate decades out. 

"Seasonal to sub-seasonal forecasting is really hard," he said, adding that "no one really knows" with certainty what will happen this winter.

A La Nina event would have a series of cascading impacts, he said, but it is "impossible" to know at this point what will happen and if it would ease the multi-year drought.

"We won't know for a bit yet," he said. "But irrespective of that, if there's been a long, severe drought, and if that drought has managed to kill off a lot of vegetation, no matter what the winter is going to be like, you are probably looking at a higher than average probability of landslide activity."

Rieder said about half of BC Hydro power outages are caused by trees and adverse weather, usually wind. She said the province has also seen an increase in infrastructure damage in the last decade.

She noted that last year, following the worst wildfire season in B.C. history, the first wind storm of the season caused damage that left 235,000 customers without power. 

"We've stepped up our vegetation management in recent years," Rieder said, adding there are now 52 BC Hydro offices across B.C. "So, when a storm does hit, we are very much able to respond quickly and have the crews in the right places at the right times."

But, she said the utility encourages residents to prepare for a potential outage by making an emergency kit that includes a flashlight and non-perishable goods that would last at least 72 hours. She noted the company's website also has an outage checklist that people can use to prepare.

This report by The Canadian Press was first published Oct. 2, 2024.

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