KAWARTHA LAKES-From wildfires to snowfall, autumn in Canada is one of the country’s most weather-diverse times of the year. With unique climates spanning from the Pacific coast to the Atlantic coast and vast temperature ranges from the Great Lakes to the Arctic Circle, it may be hard to believe that one specific phenomenon could set the stage for how the weather will shape up across the entire country, but that just may be the case this autumn according to meteorologists at AccuWeather.
That season-determining phenomenon is known as La Niña, and it stems from thousands of miles away in the central and eastern tropical Pacific Ocean. AccuWeather forecasters released their annual Canada autumn forecast this week, and they pointed to that pattern as a major factor behind the anticipated trends this season.
“La Niña conditions are anticipated this fall, which will likely play a key role in the average weather conditions across portions of Canada during this upcoming season and even perhaps into winter,” AccuWeather Senior Meteorologist Brett Anderson said.
Anderson has been providing expert forecasts and analysis on both Canada weather and climate change for decades.
Fall will officially begin with the autumnal equinox on Sept. 22, but meteorological autumn is just around the corner, starting on Sept. 1. For some, it may feel like the transition into the new season will happen quickly.
The aforementioned La Niña conditions will play a significant role along the Pacific coast of Canada this upcoming season.
The La Niña phenomenon is the abnormal cooling of the surface waters of the Pacific Ocean near the equator, which can influence the strength and position of the jet stream across North America, Anderson explained. Its influence on the Pacific jet stream plays a crucial role in directing the course and impacts of storms.
“The jet stream is like a pathway for storms, thus we are expecting a stormier fall, especially across the western half of British Columbia, with above-normal rainfall,” he said. “Large portions of British Columbia have been under severe drought and dealing with a tremendous amount of fires and poor air quality this summer.”
Could wintry conditions make an early arrival?
Elsewhere in the country, a colder-than-normal fall could be in store for the areas around British Columbia in the Yukon Territories and Alberta. Fueled by the La Niña-influenced storms, the pattern could mean early snowfall for some.
According to Anderson, snow may appear earlier than normal in the coastal mountains of British Columbia and farther east into the Canadian Rockies, which stretch into Alberta.
“Parts of northwestern British Columba and the Yukon may end up with a colder fall compared to normal as a majority of cold outbreaks may be directed into this region from eastern Alaska,” he said.
In the Canadian Prairies, which spread throughout much of the country’s midsection, an influx of storms to the north may prevent that cold and snow from dropping into the southern Prairies.
In place of that cold and snow, the southern Prairies are likely to have a much different fall.
“This type of storm track will also mean a windier- and drier-than-normal pattern for much of the southern Prairies, which have been hit hard by drought this spring and summer,” Anderson said.
Mild warmth elsewhere
The season will play out much differently farther east. In place of wildfires, drought, choking air quality or early-arriving snow, much of eastern Canada can expect a mild fall, Anderson said. Conditions will stay placid around the major cities of Toronto and Quebec thanks to nearby water temperatures.
“Above-normal water temperatures throughout the Great Lakes will likely persist through the season,” Anderson said. “This will have its biggest influence on nighttime temperatures, being milder, across the region.”
Milder air won’t mean “perfect conditions” every day for the entire season, however. Anderson noted that shots of cold air could penetrate Ontario and northern Quebec later in the season, while severe thunderstorms from the summer could linger into September for the provinces.
Even farther east, the Atlantic’s sea-surface temperatures could swing a number of factors for the provinces of Nova Scotia, New Brunswick, Prince Edward Island, Newfoundland and Labrador.
In regards to temperatures, warm-weather fans can rejoice that the combination of higher sea surface temperatures and an active storm track will likely mean above-normal temperatures.