Ag Weather Forum

Mild Pattern To Last Another Week For Canada

Doug Webster
By  Doug Webster , DTN Senior Ag Meteorologist

Winter has mostly been on hold during December for most of the Canadian Prairies but not without a couple of brief cold shots and a little snow here and there. The mild temperatures of the recent 10 days has also depleted some of the snow cover that was created during November leading to some concern for some of the winter wheat crop.

There is increasing evidence that winter may make a return during the last week of December and possibly in a big way. For nearly a week the computer models have been telling us that another episode of high latitude blocking may be in the works for North America to end 2014 and to begin 2015.

During the fall and early winter we have been in either a blocking pattern or an El Nino type weather pattern across North America. It appears that when any high latitude blocking develops that it disrupts the El Nino induced weather across North America and brings on a big dose of winter weather. This was the case during the middle of September and again during most of the middle half of November.

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During these periods temperatures fell to well below normal levels with even some record low values recorded across parts of the Prairies. Snowfall was also plentiful during each of these periods. As soon as the high latitude blocking breaks down and disappears we see a fairly quick return to the mild El Nino conditions as Pacific air pushes east across the North American continent.

Unlike last winter when the blocking patterns were stubborn and never really let up it appears this winter we are in store for episodes of each type of pattern. The result is likely to be some rather extreme changes in temperature over time with each pattern potentially producing abnormal readings.

Our current spell of mild conditions looks like it will begin to collapse during the middle of next week as a ridge builds northward along the west coast of North America shutting off the moderating influence of the Pacific. This in combination with a developing upper level high pressure area north of Alaska later this month should put in place a new cold air making machine across Canada.

Given the time of year we would expect to see a couple of rounds of possible extreme cold after Christmas and into the early part of January. More than likely the turn to cold weather will bring a couple of rounds of snow as upslope conditions develop. This would be good news for those concerned about losing some of the protective snow cover for winter wheat.

With confidence increasing as to the unfolding turn to cold weather later this month we will start to try and determine how long the cold regime lasts. Given the track record of the past few months, an early guess would be in the 2 to 3 week long time frame before a return of milder conditions.

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

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JERRY KOCHANIUK
12/18/2014 | 12:05 PM CST
Thanks for the warning.