Recent Chill a Possible Sign of an Early Winter?
So far, the month of September has brought it's fair share of extremes across Canada and the U.S., but do these recent weather patterns give us any clue about the rest of fall and the upcoming winter?
This week for instance, an air mass more typical of late October settled in across eastern Canada, leading to an early freeze/frost across parts of the region.
Looking back at years where there was a period of unusually cold weather during mid-September in Ontario and Quebec we find no real pattern in terms of what the upcoming winter was like. There were a few years that were cold and dry, some were quite mild and others were fairly normal. However, there was one common factor that did stick out and that had to do with the month of October. A clear majority of Octobers following an early freeze/frost in September ended up warm compared to normal in eastern Canada.
Also, based on the current data that I am looking at, I would not be putting away the shorts quite yet as an Indian Summer-like pattern appears to be shaping up across southern Canada the last week of this month and into early October as the cold air gets trapped across the far north.
El Nino impacts?
This year we are likely headed toward a weak El Nino and when we look back at weak El Nino winters over the past 50 years we can see (map below) that the core of below-normal temperatures were centered over the eastern half of the U.S. and extreme southeastern Canada.
Weak El Nino winters also tended to be dry in British Columbia and stormy across Atlantic Canada.
September snowfall in Calgary
The early-season snow event that impacted parts of Alberta between Sept. 8 and 10 was unusual, but not unprecedented. Looking back over the past 20 years when there was an early-season snowfall in Calgary, we see that on average the upcoming winter was generally colder and drier compared to normal, but not in all cases.
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There are many other factors such as snow cover, ocean temperatures and wind patterns that we will have to consider when making up the AccuWeather.com Canada winter forecast, which will be released later in October. Stay tuned!
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