Ag Weather Forum

El Nino Showing Up In Prairies Weather

Doug Webster
By  Doug Webster , DTN Senior Ag Meteorologist

Western Canada's crops are almost all in the bin and while it had been a good harvest yield-wise there have been quality issues for crops this fall due mostly to the early September frosts, freezes and snow. Most areas have reported quality levels well below that of both 2012 and 2013 despite yields that are above the 10-year average.

Soil moisture levels continue to be good this fall supporting the establishment of any fall seeding. The milder-than-average October has also been an aid to getting fall planting in the ground and started.

As we wrap up the 2014 crop season, we start to increase our focus on what the 2014-15 winter may hold in store for Western Canada. Last winter's bitter cold and snow were a result of pronounced upper level blocking across northern and northeastern Canada combined with a neutral ENSO pattern.

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The circumstances are definitely different as we move toward the start of November this year. While an El Nino is not officially in place by government definition, we do see many of the signals of an El Nino across North and South America. Another stark difference from this time a year ago is the complete lack of blocking across Canada and the high latitudes in general. The main polar vortex has been making a home on the Asian side of the northern hemisphere so far this fall, not across north-central Canada.

These differences from last fall could have a major impact on our winter's weather if they stay in place. The current pattern as it is set up would favor a mild weather pattern with infrequent periods of precipitation across the Prairies. The million dollar question is whether and how long can this pattern maintain itself?

Model projections are indicating that we may look forward to more mild weather well into if not through November. A mostly west to east flow is forecast across Canada and the U.S. for the coming few weeks which brings lots of Pacific air inland across the North American continent. This air is quite mild versus normal at this time of year.

The pattern as it is shown now prevents the development of Arctic high pressure across northern and northwestern Canada. The cold air making machine of last winter is nowhere to be found for now. Down the road we will have to monitor for any shifts of the position of the polar vortex and whether or not some high latitude blocking returns.

While everything looks rosy now, history tells us that drastic changes can take place. There have been years when mild conditions prevailed into early winter than the bottom dropped out. For now, we can be cautiously optimistic that we will not see a repeat of last winter, at least with the nearly endless cold and snow. Even in the most mild of winters there are a few periods of cold and snow.

The key to the upcoming winter pattern will be if and when any high latitude blocking high pressure develops and where the polar vortex decides to be. If the polar vortex stays more on the Asian side and blocking is minimal then the milder El Nino aspect of the pattern is likely to be a more important player. If blocking returns along with a stronger polar vortex across North America then the El Nino pattern will be disrupted.

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

(ES)

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