The relatively mild weather across the western Prairies during the past few weeks is history as the arctic cold has returned to all of the region during the past day or two. Below- to well-below-normal temperatures will again be the rule for all of the Prairies during the coming week.
So far during January average temperatures have varied from several degrees below normal across Manitoba to several degrees Celsius above normal across Alberta where arctic chill has been scarce most of the time. Snowfall has been near or a little less than normal and the mild readings across the western Prairies have even cut into the snow pack.
The endless supply of arctic air across Canada this winter continues to be brought about by a blocking high across Alaska and eastern Siberia and a polar vortex across the Hudson Bay region and northern Quebec region of Canada. This cold air manufacturing machine has been in place for about three months and shows no signs of breaking down through the first part of February.
There is enough of a shift taking place with the positioning of the upper air features across North America to allow for all of the Prairies to share in the cold pattern once again. The strong upper air ridge across Alaska, which brought record warmth there, is nudging a little to the west, allowing the northwest to southeast jet stream flow across Western Canada to shift from the eastern to the western Prairies. While not a wholesale change in the pattern for Canada, it is enough to allow the arctic cold to retake far Western Canada, producing a pattern much more like we saw during December.
Across the U.S., a developing southern stream jet will increase the winter storm threats during the next week or two but it appears that most of this moisture will stay south of the Prairies with mostly a dry, very cold pattern dominant north of the border. December brought sizable snows to the Prairies, but this time around it appears snow amounts may be a little meager based upon where the main storm track is expected to set up. Most of the expected snowfall will come with cold fronts every few days which tend to produce only light amounts.
Some of the longer range model products hint that by mid or late February we might see a return of milder weather for the western Prairies but this is certainly not a lock. These same models are forecasting precipitation amounts to be a little less than average for February across the Prairies.
Blocking patterns across the northern latitudes have dominated this winter. As we think about how soon will winter's chill ease and spring planting prospect unfold, the key will be the speed of how those blocking patterns break down during this spring.
Hopefully we will not see a repeat of last year's extended winter and late planting.
Doug Webster can be reached at firstname.lastname@example.org
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