After a fall filled with weather kind to farmers allowing for a great harvest, we look increasingly toward what the late fall and early winter weather patterns will bring to Western Canada. Each day complex computer models churn out forecasts that extend outward from a few days to a few weeks.
Clues about the upcoming winter season sometimes are gathered from weather patterns across the globe during October and November. Some of these clues include snow cover increase and extent across Siberia to sea surface temperatures across the Pacific and Atlantic Oceans to whether or not high latitude blocking patterns are appearing across the Northern Hemisphere. Other patterns that computer models identify are also looked at to try and come up with whether winter will start with a rush or be benign.
Some of the more recent clues point to a possible upper air pattern during the next few weeks that could bring increasingly cold weather and snow to the Prairies not too far down the road. Yes, it's November and snow and cold normally increase, but we're talking about colder-than-normal weather and the threat of above-normal precipitation to go with it.
Some of the climate models are forecasting a ridge to become more dominant through the Gulf of Alaska to Alaska allowing the jet stream to flow northward into Alaska before shifting southeastward across Western Canada. This pattern tends to close off the modifying influence of the Pacific Ocean for Western Canada and allows for the development of surface high pressure across eastern Alaska and northwest Canada.
High pressure during late fall across what is now becoming a snow-covered northwest Canada allows temperatures to drop quickly during the long nights and not recover much during the day. This is how arctic air begins to become established as we move toward the winter season.
Model forecasts for November are showing that below-normal temperatures and above-normal precipitation may be in the cards for the Prairies. Both the U.S. and Canadian climate model outlooks for November are offering a similar scenario with the U.S. models more aggressive.
Shorter-range model forecasts for the first week of November are still fairly kind to Western Canada but as the second week arrives, a trend to colder and possibly snowier weather is implied. With the harvest pretty much complete, it's time to get out the overcoat and snow shovel and throw another log on the fire.
Doug Webster can be reached at email@example.com
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