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Stormy pattern to emerge in western Canada
La Niña conditions can alter the overall atmospheric pattern in multiple ways. One of the most significant factors for this fall's forecast will be how La Niña affects the position of the jet stream. The position of the jet stream determines the general track of stormy weather and, depending on the position, certain regions can be in for a much wetter or, conversely, a much drier season.
"An active, Pacific storm track is anticipated to be directed into British Columbia this fall, which will favor above-normal rainfall and cloudier, cool days," Anderson said.
One of the most devastating flooding events in the history of British Columbia occurred during the La Niña-influenced fall of 2021. In November 2021, epic amounts of rainfall triggered deadly flooding across portions of southern British Columbia that displaced thousands of residents, washed away bridges and roadways, cut off railroad routes and drowned livestock.
While a repeat of 2021's calamitous flooding is unlikely given that event was a 500-year flood, or a flood that has a 1 in 500 (0.2 percent) chance of occurring in a given year, other heavy rain events cannot be ruled out this fall.
In addition to rainfall, any stronger storms that track through British Columbia and the rest of western Canada can also bring windier conditions when compared to normal, according to Anderson.
Heavier storms can bring localized flooding concerns, but any rainfall will work to ease wildfire concerns by reducing the amount of dry fuel available.
"The projected weather pattern this fall should favor conditions that will help with fire suppression," Anderson said.
In terms of temperature, waves of colder, Arctic air are forecast to impact portions of western Canada this upcoming season due to the anticipated position of the jet stream.
"The coldest air relative to normal for all of Canada is expected across northwestern Canada, specifically northern British Columbia, the Yukon Territory and the western portion of the Northwest Territories," Anderson said.
In addition, the pattern this fall may also lead to an earlier-than-usual start to the snow season in the Coastal and Rocky Mountains, according to Anderson.
In places like Vancouver and Abbotsford, this fall is expected to be fairly normal when it comes to temperatures, but overall precipitation is set to surpass seasonal averages.
Fall/Winter 