With A beast of an El Nino pattern starting to really effect the jet stream and makes forecasting quite easy. It is one of the heaviest factors in forecasting. The other factor that can effect winter weather is the Arctic Oscillation which is currently in the positive phase. This strengthens the Jet even more locking the cold air in the Arctic.
Currently the warm and dry bias is very high and aside from a single 3 or 4 day cold snap the month of December should be above to well above normal and dry to very dry. Anomalies are likely to finish off in the +3-8C range in a wide swath of central Alberta and southern Alberta. The extreme north should also get a good 2C warmer than normal.
Snowfall is expected to be very low, Cities like Edmonton may struggle to maintain snow cover while Calgary could spend most of the winter without any snow cover. Regions that received more than 8″(20cm) during the November storm have the best chance to maintain snow cover into the new year. Mild and dry winters actually lead to more winter kill of perannuals and winter crops due to a lack of snow cover and false germanation. Winter nights are long and can still get very cold, even if the daytime gets well above freezing.
Anomaly Maps for December
December in detail:
Dec 1-10: Very mild, little or no snow to speak of. More likely to see more freezing rain in the north.
Dec 10-20: Remaining very mild, turning colder.
Dec 20-31: Possible snowstorm around Christmas followed by a 3 or 4 day cold snap. Becoming very mild once again toward the new year. 2016