Another month has come and gone and just as quickly as summer arrived across the Prairies in May, it left about halfway through September.
After three to four months in a row of near- to above-average temperatures, we saw a blocking pattern develop across the eastern Pacific that allowed cold arctic air to dive well south of its usual late-summer/early-fall position. Along with the cold air also came precipitation, with several locations reporting above-average precipitation during September.
Looking at the weather numbers for September, the coldest regions, both in terms of absolute temperatures and compared to average, were found across Alberta. Mean monthly temperatures ranged from 3.5 C below average in Calgary to just over 5 C below average in the Peace region. Saskatchewan fared only a little better, with both Regina and Saskatoon reporting mean monthly temperatures around 3.5 C below their long-term averages. It took a little longer for the cold air to invade Manitoba. As a result, mean monthly temperatures were a little warmer, with temperatures ranging from 2.5 C below average in the Brandon and Dauphin regions to about 1.5 C below average in the Winnipeg region.
As I pointed out in the beginning of this article, the colder weather also brought above-average amounts of precipitation to some parts of the Prairies. Starting in Alberta, the southern and northern regions saw below-average amounts of precipitation, with both Calgary and Peace River reporting about 25 mm. Across central regions it was a different story, with the Edmonton region reporting over 70 mm of precipitation, about 30 mm above average. Across Saskatchewan, precipitation was near average, with Saskatoon reporting about 35 mm, which is right around average, and Regina, reporting about 25 mm, which is a little below average. Manitoba was the wet spot, with all three stations reporting above-average amounts of precipitation. Thanks to some late-season thunderstorms, the Winnipeg region was the wettest location across the Prairies, with around 115 mm of precipitation. This is about 60 mm more than average.
Who called it?
Overall, across the Prairies it was colder and either near or wetter than average in precipitation. Looking back at the different forecasts, it appears that both the Canadian Farmers’ Almanac and the CanSIP model did the best job in predicting September’s weather. The Canadian Farmers’ Almanac called for a cool and wet month while the CanSIP model called for cooler-than-average temperatures and near-average amounts of precipitation. I think we could call it a tie, but I will let you decide.
Now, on to the most important part of this week’s article: the latest long-range forecasts for the next few months. Environment Canada’s probabilistic and deterministic forecasts call for October to continue with below-average temperatures and a slow warming trend to above-average temperatures by November and December. Moving on to Environment Canada’s CanSIP model, its latest forecast calls for near-average temperatures in October with above-average precipitation across the eastern Prairies and near-average amounts across the west. It then calls for above-average temperatures in November and December, especially over Alberta, with near-average amounts of precipitation.
Moving on to the two almanacs. The Old Farmer’s Almanac calls for above-average temperatures in October across the eastern Prairies with below-average temperatures in the west. Precipitation is forecast to be above average across all three Prairie provinces in October. November and December are forecast to be cooler than average with near-average amounts of precipitation in November and above-average in December. The Canadian Farmers’ Almanac is a bit of a broken record as it calls for cold and wet weather for October, November and December. It even calls for a big Christmas Day snowstorm.
Looking to the U.S. forecasters, NOAA calls for near- to slightly above-average temperatures from October to December, with average to slightly below-average amounts of precipitation. The Weather Network calls for near-average temperatures over the eastern and central Prairies, with slightly above-average temperatures in the west. It also calls for near-average amounts of precipitation with below-average amounts across southern Alberta.
Finally, my forecast. It looks like the current cold pattern is going to hold on for most of October, which means a continuation of below-average temperatures. Cold fall weather often coincides with above-average amounts of precipitation as the cold air bumps up against warm air to our south. So, I will also go with above-average amounts of precipitation. I think we will see a switch to above-average temperatures sometime in November; just how quick that switch will be is the million-dollar question. Going on my gut feeling, which doesn’t always work out, I feel that November will see near-average temperatures along with above-average precipitation, followed by a warmer- and drier-than-average December.