During the past several days, we have seen enough of a change with the upper air jet stream flow to allow for weather more in keeping with the middle of December to descend upon Western Canada. A week ago it appeared that this would happen, but that it would be only a brief break in the very mild pattern created by El Nino.
During recent days most of the guidance has come around to the idea that Western Canada may keep the more seasonable weather pattern for most of the remainder of December. A general area of trough is expected to make a home across the western U.S. and parts of southwest Canada. While we are not expecting arctic air to arrive bringing bitter cold, we do expect temperatures to average closer to normal for this time of year for the next week or two.
During a normal El Nino, the warmest weather anomalies are generally found across Western Canada to western Ontario but during the next couple of weeks this core of warmth is expected to be found from eastern Ontario to Quebec and eastern Canada. With this idea in mind, we would expect the eastern Prairies to be a little milder than normal while the west may be normal or even a little colder than normal at times.
The chillier weather outlook is created by a southward shift in the location of the jet stream from Western Canada to a flow into the West Coast of the U.S. With the location of the main jet stream to the south of the Prairies, we can expect temperatures to be more in line with late December despite the general lack of arctic air across Canada still.
There now exists a snow cover across much of the Prairies, though thin in many areas, and this will help create a colder environment coupled with the longs nights this time of year. The accompanying chart from Environment Canada depicts the general snow cover now in place across much of the nation with only southeast Ontario and southwest Quebec still snowless due to the unseasonable warmth of late there.
While we are expecting temperatures to be more in line with the time of year during the next week or two, we do not expect too much in the way of precipitation. The main storm track will be mostly to the south of the region for the remainder of the month with any snow likely to be light and spotty.
With a strong El Nino still in place, we will have to watch for a warming trend at some point as we move deeper into January, since there is strong correlation to warmth across the Prairies with an El Nino.
Doug Webster can be reached at firstname.lastname@example.org
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