Arctic air has taken over across much of central and western Canada and down across the western half of the U.S. during the past few days, sending temperatures to well below normal levels. Bitter cold temperatures along with windy conditions at times will continue to make being outdoors rather miserable for these areas.
A large arctic high pressure area extending from eastern Alaska down through western Canada will keep mostly dry weather in place, but by early next week we may see some light snow fall across the Prairies as a reinforcing shot of cold arrives. Snowfall prospects may improve by late next week and beyond as the weather pattern undergoes some changes.
These changes will most likely not improve cold conditions for the Prairies during the pre-Christmas period but should increase the snow threats. The deep trough now across the western part of the continent is expected to shift into a more west-to-east flow in about a week, allowing for a series of low pressure areas to move in from the Pacific, traveling along or just south of the U.S./Canadian border. Arctic air banked up across much of Canada will probably not be dislodged and will act as an overrunning surface for moisture with the result being more snow.
Some of the longer range model output does show some improvement in the temperature department as we move to the tail end of December and January. While confidence is low as to the development of warming temperatures, there has been fairly good consistency with model forecasts bringing a reversal in temperatures by the time we reach January for the past several days.
Since ENSO conditions look like they will continue to be neutral for the next several weeks, we tend to favor the idea that wide ranging weather events are more probable than not for the Prairies this winter. Temperature extremes of both cold and warm are a good possibility. While severe cold now covers the region, don't be surprised if warming Chinook winds develop in a few weeks only to be followed by another cold siege later on during the winter.
Typically we do not see unseasonably cold weather last for weeks on end and it would be more normal to see some sort of a temperature rebound before we get too many weeks into the future.
Doug Webster can be reached at email@example.com
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