Since the middle of November we have seen a high occurrence of arctic air across northwestern Canada southeastward into the Prairie region. Temperatures have averaged below to well below normal most of the time with actual temperatures falling to as low as -10 to -25 F (-23 to -32C) on some nights across the region.
The upper air pattern across Alaska and western Canada has been promoting a large surface high pressure area through western Canada allowing for the development of arctic air. Lacking are the stronger storms that sometime push inland from the Pacific bringing periods of much milder readings so far this winter. During the past few days temperatures moderated some from last week's bitter temperatures but not to the levels we had envisioned. A pattern that looked like it would produce near normal temperatures for a few days only was able to muster readings in the below normal category.
An extensive snow cover of 5 to 12 inches (13 to 30 cm) across Alberta, Saskatchewan, and Manitoba is helping to maintain the cold pattern and more importantly is giving protection to most of the winter grain crops from the cold. We are also seeing intermittent periods of light snow which adds a little more protective snow cover to the region.
The outlook for the remainder of December seems to be pointing us toward a continued colder than normal temperature pattern for western Canada with arctic air holding a firm grip on the region. As arctic high pressure strengthens across northwest Canada next week and expands southeastward we should see a return of readings like we saw a little more than a week ago. Nighttime temperatures may fall to 20 to 30 degrees below zero F (-29 to -34C) on some nights next week with daytime readings probably staying below zero F (-18C) as well. This type of weather pattern may last into the beginning of the new year. A few periods of light snow or flurries can be expected from time to time but most likely no important storms will occur with this pattern.