Modified polar air made a visit to Western Canada during the first few days of November to bring most areas a taste of a little snow and the coldest readings of the season to date. Compared to what we can see at this time of year, the chillier weather was not anything to write home about.
A strong El Nino remains a major player in the overall weather pattern across the Pacific and North America and probably took the edge off the recent cool spell. Cold air has had trouble accumulating across Canada thus far due to the El Nino as Pacific air has been moving from west to east keeping mostly moderate weather in place and delaying the southward push of snow cover.
The accompanying snow chart shows last night's snow cover across Canada, with the dotted line being where snow cover usually is as an average by this date. One can see that only a thin cover exists across the northern Prairies, while we typically see snow cover all the way southward to near the U.S. border across Saskatchewan and Manitoba by this time.
Snow cover helps cold air develop at this time of year and the lack of snow coupled with the mild flow from the Pacific keeps the cold air making machine out of the picture for now. While it might appear winter was about to take hold during the past few days, we are more likely to see rather mild weather return this weekend.
The overall weather pattern continues to favor fairly long episodes of mild weather and much shorter periods of colder weather during the next 10 days. We will have to keep an eye on things for the third week of the month as it appears Alaska will turn much colder in about one week and some of this cold air could make its way southeast into Western Canada around the third week in November. This is by no means a sure bet.
Longer range forecast models continue to show modifying Pacific air flow into western and central Canada into December. Nearly all of the nation is forecast to see above normal temperatures during December. It's important to remember that this is an average for an entire month and that a few short bursts of cold, snowy weather are still quite likely despite the mild monthly average.
Important factors to help induce winter weather will be how fast snow cover becomes established across the Prairies and how persistent the Pacific flow is as we move deeper into the winter. Any time the Pacific flow of mild air stops for a time, we will likely see a pool of cold or very cold weather develop across parts of western or central Canada. With El Nino in place, these cold occurrences are more than likely going to be few and far between.
Doug Webster can be reached at email@example.com
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