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AccuWeather Canada Winter forecast
The winter of 2015-16 could end up as one of the warmest winters on record for Canada as a whole as a very strong El Nino persists into the upcoming season.
Despite the unusual cold across the eastern half of the country the past two winters, Canadian winters have been trending warmer since the middle of the 20th century, warming an average of 3 degrees Celsius over the past 67 years. Most of that warming has been across the northern half of the country.
Confidence is higher than usual that Western Canada residents should expect another winter with above- to well above-normal temperatures, as a prevailing westerly flow delivers milder, Pacific air across the region.
Compared to last winter, there will be more snow across the Coastal mountains of western British Columbia, which includes the Whistler/Blackcomb ski resort. Farther east in the Rockies of eastern British Columbia and western Alberta,snowfall will underachieve this winter. Most of the snow in this region will fall during the first half of the winter before a drier pattern sets up during January and February.
Drier and milder weather will be a dominant theme across the Prairie region this winter as the polar jet stream gets displaced farther north. This pattern will greatly limit the amount and duration of Arctic air masses that normally impact the region. Average temperatures could be as much as 3 degrees Celsius above normal this winter in cities such as Edmonton, Calgary and Regina.
Significant snowfall events will be few and far between across the region as the primary storm track will generally remain too far to the south across the central and southern U.S.
Ontario and Quebec
This coming winter will not be nearly as cold as last winter thanks in part to El Nino. This should lead to a noticeable difference in heating bills compared to last year. Unfortunately, the winter pattern will also favor an increased risk of ice storms, especially from eastern Ontario to southern Quebec, including the cities of Ottawa and Montreal as temperature inversions will be more common. Much of Ontario, including the lake-effect snow belts, will have less snowfall compared to normal, as the main storm track shifts too far to the south and east during January and February.
As the storm track shifts toward to the East Coast later in January and February, there will be an increased risk for significant snowfall events across eastern Quebec, including the Gaspe Peninsula.
The combination of a strong El Nino and warmer-than-usual sea surface waters surrounding the region will lead to slightly warmer temperatures compared to normal this winter. The winter could turn snowy again from New Brunswick to Prince Edward Island, especially the second half of the winter.
The milder conditions will favor a greater tendency for storms that initially bring snow but changes to ice or rain, especially across Nova Scotia.
Much of Newfoundland will experience a milder winter with a reduced number of major storms.
Some additional thoughts:
There was unusually good consensus among computer models and analogs in regards to the temperature and jet stream pattern for this winter. Much of that is due to the ongoing strong El Nino.
However, there are some questions. Will the warm blob of water, which has been sitting off the West Coast for the past two years enhance or weaken the impacts of El Nino?
Will the blob of abnormally cold water southeast of Greenland (due in part to the intrusion of fresh water from the melting of the ice sheet) have any type of impact?
Unusually warm water also surrounds Atlantic Canada and we think this will persist into the winter. The impact of that would be some moderation in temperatures for coastal Atlantic Canada, increased cloud cover and more fuel for any coastal storms. Snow cover extent so far this fall in Canada is running behind schedule in northwestern Canada but ahead of schedule east of Hudson Bay to western Labrador. Could this have an impact on the start of winter?
Some research states that the rate of growth of the Eurasian snow extent during the month of October is related to the primary phase of the Arctic Oscillation later in the winter. If the snow extent increases at a higher rate compared to normal then that tends to favor a negative phase of the Arctic Oscillation (AO) later in the winter, which in turns favors a southward shift of the Arctic air into southern Canada and the northern U.S. So far this month the Eurasian snow extent is increasing at a slightly higher rate than normal, but not as high as October 2014. We may have to wait another 10 days to see where it stands. Generally, there is forecast skill out to two weeks in terms of being able to predict the strength and phase of the AO or NAO. Once beyond two weeks, there is much higher uncertainty.
I can't recall ever putting out a winter temperature outlook that had such a large area of above-normal temperatures. Once again, confidence in the temperature outlook is higher than normal for western Canada and less as we go east, especially from central and eastern Ontario through southern Quebec as there is the potential for bitterly cold intrusions coming down from the Hudson Bay region, especially during the second half of the winter. The current forecast projections would suggest that most of these cold intrusions would be brief, especially if there is a lack of upstream blocking.
You can also follow my commentary of the weather via my twitter account @BrettAWX
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