Should Canadians be pulling out their snow boots and cold-weather clothes as we inch closer to winter? Maybe.
“Our current seasonal predictions are tilting the odds, particularly in British Columbia, slightly towards a colder than usual winter” says Bill Merryfield, a research scientist with Environment and Climate Change Canada. “The odds slightly favour warmer than usual temperatures in most of the eastern half of Canada,” he adds.
These predictions stem from an anticipated La Niña climate pattern, often characterized by cooler than normal temperatures in the southern parts of the Pacific Ocean. “Our system has been predicting there should be a La Niña this winter,” says Merryfield, adding that the system tends to bring the cold to Canada, particularly its western parts.
“If that prediction is correct, there will have been four La Niña winters in the past five years, which has happened only once before since 1950,” he says.
Farmers’ Almanac predicted “above normal precipitation” this winter over parts of eastern Canada and the Great Lakes, meaning rain and slush for these areas. They say conditions are favourable for snow in Quebec and Ontario, with Ontario seeing rain as well.
Earlier this month, The Weather Network assessed previous Canadian winters with a weak La Niña to try to get a sense of what this winter will bring. They suggested we could see a “strong start” to winter in December, and possibly colder than usual temperatures this November. January and February are more uncertain and could lean towards colder or milder temperatures depending on how conditions develop in the coming weeks.
Merryfield says that since a warmer than normal winter is expected for the eastern parts of Canada, the odds are increased for a below normal snowpack. Over in Western Canada, he says there’s no clear answer whether they’ll get more or less snow than usual.
He adds that predicting seasonal climate is challenging. Researchers do so by combining the techniques used to predict weekly weather reports, as well as the models used to predict long-term climate trends. The models simulate changes in the atmosphere, ocean, and sea ice cover, among other climate elements.
If you live in a landlocked part of Canada, you might not consider the effect the world’s oceans have on your daily life. But they’re key to predicting seasonal climate.
“For weather forecasts over the next week or so, it doesn’t really matter what changes are occurring in the ocean, because those are fairly gradual and don’t have a strong influence on day-to-day weather,” says Merryfield. “But over longer periods, ocean surface temperatures have a very strong influence on how climate or weather patterns vary around the globe.”
We’ll have to wait and see what the ocean temperatures have in store for us this winter, but as of right now, it sure looks like a mixed bag.
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