Winter is now. Here's how we develop our winter forecast

Monday, December 14, 2015, 1:16 PM - El Niño has a reputation for bringing mild winters to most of Canada and we are in the midst of one of the strongest El Niño events on record. In addition, most of Canada has experienced a warmer than normal fall. Does all of this mean that we are in for a mild winter this year? 

You can find the exact answer to that question in The Weather Network's recently released Winter Forecast.

In the meantime, Meteorologist Dr. Doug Gillham provides some insight on the process for developing our winter forecast.   

WINTER FORECAST: Here's everything you need to make it through the coming season

Can you really forecast the weather for the next three months?   

Yes and no. If you want to know if it will snow on Christmas or the high temperature on Valentine’s Day, you will have to wait a while for a forecast with those details.   

Seasonal forecasts do not attempt to provide the details that you look for in your daily forecast – such as when will the snow start/end. Our winter forecast provides an overview of the dominant weather patterns that we expect for the upcoming season (such whether we will have a mild winter or a cold winter).   

While forecasting the dominant weather patterns for an entire season is still a difficult challenge (that we don’t always get right), this is often less tricky than forecasting how much snow will fall on your driveway on one specific day. 

What is the process for doing a winter forecast? 

First, we are continuously tracking weather and ocean water temperature patterns around the world. We are looking for signs that current patterns will continue or change as we go into the next season and beyond.

In addition, we use computer models which are produced by weather services around the world. These models have limited success in predicting how large scale patterns around the world will develop and change during the weeks and months ahead. 

Understanding the patterns and how they should evolve is critical to being successful. The models will often disagree with each other or come up with forecasts that does not make sense meteorologically and we need to be able to recognize those errors.

We also seek to identify years in the past that had similar global weather and sea surface temperature patterns and study the weather patterns across North America that were associated with those years.

Years in the past that had similar patterns to our current patterns are called analogue years. Identifying the correct analogue years and researching their associated weather patterns will usually be more helpful than the computer models when it comes to forecasting the weather patterns for upcoming seasons.

Are there any clues can be found in the weather from the fall to forecast the upcoming winter?  

Typically, our fall weather pattern does not necessarily tell very much about the upcoming winter season. While there are many examples of mild falls that were followed by mild winters (and vice versa), there are also examples of mild falls that were followed by cold winters (and vice versa). 

However, temperature patterns during the fall do impact water temperatures in the Great Lakes, which does have some impact on winter temperatures near the lakes and on the lake effect snow season.

In addition, the weather in other parts of the world can offer some clues as to what the winter may bring. Above average snowfall in Siberia during the fall has been linked to colder winters across central and eastern Canada.  During this past fall the snow cover across Siberia has been well above average.

However, one should not jump to conclusions based on this observation alone as there have been exceptions to this connection. In fact, the fall that had the most extensive snow across Siberia was actually relatively mild across Southern Canada.