Ag Weather Forum

Mild Winter Outlook for Canadian Prairies

Doug Webster
By  Doug Webster , DTN Senior Ag Meteorologist
Jet stream patterns with El Nino leave the Canadian Prairies in between the main tracks, with a mild and dry pattern for winter. (NOAA Graphic)

The majority of the 2015 western Canada crops have been harvested or will soon be in the bin. A pretty good harvest season has been had from a weather perspective, and with another week of good harvest weather ahead, most areas should be completely finished with harvest by the end of next week.

A strong El Nino remains in place across the Pacific, and we are focusing more attention on its impact on the weather across western Canada during winter months. Based on historical data, we have decent confidence that the coming winter will be considerably different than the past two season, when episodes of very cold weather and snow were commonplace with an eastern bias.

The accompanying chart depicts what we most likely will see with the jet stream flow during the next few months. As we move deeper into November and the jet stream strengthens, the warm tongue of water across the tropical Pacific will likely produce what we call a split flow pattern across North America.

The jet stream flow coming eastward across the Pacific tends to split into two streams as it nears the West Coast of North America with one branch crossing the southern U.S. bringing wet, cool weather there, hopefully with some beneficial rains to the drought-stricken West Coast.

The northern branch of the jet stream most likely will be configured quite differently this winter than the past two, and will ride northeastward into western Canada bringing mild Pacific origin air across most of western Canada and trap any arctic air that develops across northeastern Canada. A common occurrence during this type of winter will be the downsloping Chinook winds that warm and dry out as they move east from the mountains of western Canada onto the Prairies.

The main storm track should lie to the north of the Prairies most of the time, leading to less than average precipitation to go along with above normal temperatures. Despite these expected generalities for the winter season we can never rule out a few short episodes of very cold weather and even some snow, but on average the mild, drier scenario should be the winner for this winter.

Fall crops have become well-established in many areas with some beneficial rains and mild temperatures. One potential problem for the winter would be that below-average snow could leave some of the overwintering crops vulnerable to a quick cold shot if little or no snow exists on the ground to protect these crops.

Farther down the road, we will have to see how fast the El Nino weakens later in the winter and spring to see if spring planting is affected by dry weather or not. The winter pattern is more than likely to be dry; but, with El Nino expected to weaken during the spring, we may see precipitation blossom in time to allow for a decent seeding season.

It's important to note that while a strong El Nino has some strong weather connections that affect western Canadian winter weather, there have always been periods when winter does make an appearance for a time. El Nino's impacts have already been registered across North America during the past couple of months, and are sure to only become more intense during the balance of 2015.

Doug Webster can be reached at doug.webster@dtn.com

(BA)

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