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La Nina and the winter forecasts

Canada’s CanSIPS model still calls for a warmer-than-average October

La Nina winters have a slightly higher-than-average chance of being cooler and wetter than average.

Icannot believe another month has come and gone. Sometimes it seems like it was the longest month ever and other times it felt like one of the fastest. September’s weather kind of mirrored my feelings. Sometimes it seemed like fall was here to stay and at other times summer tried to make a comeback. The question is whether the summer or the fall temperatures won out overall and how it all added up at the end of the month.

Looking across the entire Prairies, it was the story of cool in the east and warm in the west. Across Alberta, temperatures ranged from nearly 3 C above average in the Edmonton region to about 0.6 C above average in the Peace region. Going hand-in-hand with the warm temperatures were dry conditions, with most regions seeing amounts that ranged from 20 to 35 mm below the long-term average.

Moving east into Saskatchewan we see things cool down a little bit. Temperatures at both Regina and Saskatoon were about 0.5 C above the long-term average and just like Alberta, precipitation was well-below average. Regina came in at just over 20 mm below average, with Saskatoon coming in at just over 10 mm below average.

The cooling trend continued as we move east into Manitoba. All three regions (Dauphin, Brandon and Winnipeg) recorded mean monthly temperatures that fell within a few 10ths of 11.5 C. Compared to average, the Dauphin region was the warmest, coming in 0.2 C below the long-term average. The Winnipeg region was the cold spot, with a mean temperature just shy of 1.0 C below average. The dry pattern seen across Alberta and Saskatchewan continued across Manitoba, with amounts ranging between 30 and 45 mm below average.

Who called it?

So, overall, it was a warmer- and drier-than-average September across Alberta and Saskatchewan, with near- to slightly below-average temperatures and drier-than-average conditions across Manitoba. Looking back at the different forecasts, no one was able to correctly catch the differences between western and eastern regions. I guess if I had to call a winner it would be the CanSIPS model for Manitoba and the Old Farmer’s Almanac and NOAA for Saskatchewan and Alberta. Even these two forecasts didn’t correctly call for the well-below-average rainfall, as they both called for near- average rainfall, but they did get the above-average temperatures.

OK, now on to the October forecasts and a revisit to the winter forecast to see if the current La Nina event unfolding across the Pacific Ocean has changed any of the forecasts.

As usual, let us begin with the almanacs. One of their points of pride is the fact that they create their forecasts only once a year and do not change them. With that said, let’s review what they are forecasting for October through to December. The Old Farmer’s Almanac calls for above-average temperatures in October with near-average precipitation. The above-average temperatures and near-average precipitation continue into November and December before below-average temperatures and precipitation move in by January. The Canadian Farmers’ Almanac appears to call for cooler- and wetter-than-average conditions in October as it mentions cool and chilly weather several times along with unsettled, showery and squally weather. For the winter, its general forecast calls for colder- and snowier-than-average weather.

Next up is NOAA; its latest forecast calls for well-above-average temperatures and a dry October, followed by slightly above-average temperatures from November through to January with near-average precipitation over the eastern Prairies and slightly above-average amounts over the western Prairies. The CFS weather model seems to be taking the La Nina conditions to heart. It is still calling for a warm and relatively dry October but is now calling for below-average temperatures right through the winter, with near- to above-average snowfall. Moving on to the Canadian CanSIPS model, it hasn’t deviated too much from last month’s forecast. It still calls for well-above-average temperatures in October with below-average precipitation. The model continues to call for slightly above-average temperatures in both November and December but has shifted to below-average temperatures in January. The model shows near-average precipitation from November through to January.

Last but not least is my forecast. La Nina winters have a slightly higher-than-average chance of being cooler and wetter than average, but with that said I don’t think we will see a whole winter of colder-than-average temperatures. I don’t think I have the guts to go against all the models calling for much warmer-than-average temperatures this October, but I think we will see temperatures cooling to near- to slightly below average by late November and into December. Along with these temperatures, I think precipitation will start off on the dry side in October and will then slowly slide toward average to even above-average amounts by December.

Now as usual, we sit back and see just how bad, or good, these forecasts end up being.

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.



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