Christmas has come and gone, December has come and gone, and 2011 is done, so we have a lot of weather to recap! In this issue we’ll only have room to discuss this December’s weather and then look ahead to see what January’s weather might be like. In the following issue we’ll take a look back at 2011 and highlight some of the interesting weather events that impacted our part of the world and then expand that to look at some of the most significant weather events that happened globally in 2011.
No matter where you were across the Prairies during December, you would have experienced pretty much the same type of weather: warm and dry, at least relative to what we would normally expect December to be like. Every single station I checked reported temperatures well above the long-term average for the month. In Manitoba, both Winnipeg and Brandon reported a mean monthly temperature of -8.3 C, a good 6 C above the long-term average. While it was a very warm month it didn’t even come close to the all-time warmest December on record, which occurred back in 1997, with a mean monthly temperature of -3.7 C. But it was still a very warm month, coming in as the fifth-warmest December on record.
If we thought it was warm across Manitoba, Saskatchewan and Alberta were even warmer. Both Regina and Saskatoon reported a mean monthly temperature of -6.3 C, nearly 8 C above the long-term average. In Alberta, Edmonton reported a mean monthly temperature in December of -5.4 C, while Calgary came in at -1.5 C. Both of those readings were about 6 C above average.
Not only was December very mild, it was also very dry. With the exception of Calgary, all major centres reported fewer than 10 millimetres of water equivalent, with most sites reporting fewer than five. Combine these light amounts of snow with the mild temperatures and you end up with very little snow cover.
Now, if you remember back about a month or so, all the talk was about how cold and snowy this winter was going to be. While there is still a lot of winter left, and we might still see cold, snowy conditions, the big question is, why did we not see the cold and snow during December?
The answer lies with what’s known as the Arctic Oscillation. This is a close relative to the more well-known North Atlantic Oscillation, and it all ties into differences in pressure between a semi-permanent area of low pressure near Iceland and a region of high pressure in the subtropical Atlantic known as the Azores High. When there is a large difference in pressure it is said to be in a positive phase and this usually results in warmer temperatures across central and eastern North America.
This is exactly what we experienced during December. The Arctic Oscillation was in an extremely positive phase, almost the complete opposite of what we saw last winter when it was in an extreme record-breaking negative phase. This allows for warm air to remain in place over our region, keeping the cold air bottled up north. The next big question is, will this pattern remain for the rest of the winter or will it become neutral or even negative, bringing the cold and snow everyone has been promising?
Who called it?
Before we look at that, we have to see who correctly predicted the warm, dry December weather. Looking back, it appears that it was us here at the Co-operator who correctly called for mild and dry conditions. Both the Old Farmer’s Almanac and Canadian Farmers’ Almanac called for either near-average or below-average temperatures and near- or above-average amounts of snowfall. Unfortunately, I realize now that I forgot to include Environment Canada’s predictions for December, so perhaps we would have been tied for an accurate prediction… but I guess we’ll never know. Sorry, EC!
Now, on to January’s weather outlook. According to Environment Canada, the southern parts of the Prairies will see near-average temperatures during the month, while northern regions will see below-average conditions. Both almanacs call for below-average temperatures during January, along with near- to above-average amounts of snow.
Finally, here at the Co-operator, I am calling for near-average temperatures during the month. After a warm start we’ll see the coldest temperatures of the season move in to bring our first really cold snap. This cold snap will last about a week before milder conditions move back in. Along with the cold temperatures moving in, we’ll have a chance of seeing some significant snow as we transition from the mild to cold conditions. Should this happen we’ll also see near- to slightly above-average amounts of snow. If we miss out once again, snowfall will be below average for the month.