Weather patterns around the Northern hemisphere during October and November normally give us some clues as to what the winter weather will be across many parts of Canada and the U.S. Since we are now moving into the middle of November, we see more signs that indicate colder-than-normal weather may happen more often than not across western and northwestern Canada during the next few months.
The clues range from a fairly persistent ridge of high pressure through the northern Pacific to a couple of early-season cold air events that have already dropped into Western Canada.
A strong ridge has persisted across the northern Pacific Ocean during the past several weeks and has produced progressive troughs from the eastern Gulf of Alaska to Western Canada at times. This process allows cold air to develop across eastern Alaska and northwest Canada and as the progressive troughs move east, cold air is allowed to drop southeastward across western to south-central Canada behind the troughs.
Current indications are that this area of Pacific high pressure at high latitudes may be a semi-permanent feature during at least the early part of winter and allow for further cold air events for the Prairies. This does not mean that it will be cold all of the time, but episodes of arctic air should be expected every several days with moderation in between. Some light to moderate snow may also fall as cold air arrives and moves uphill against the Rockies.
There has already been some history of cold weather so far this month with two arctic air masses making their mark on the region. Current model guidance indicates a new arctic surge arriving later this weekend through early next week. Like previous events, we do expect fairly rapid moderation later next week as warming westerly winds develop.
Climate model outlooks seem to be coming in line for a lower-than-normal temperature forecast for northwest and western Canada later this month as well as for December. Precipitation forecasts for the region during this time also are indicating above-normal levels of precipitation which means snow at this time of year.
Doug Webster can be reached at firstname.lastname@example.org
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