Posted on Sep 20, 2015
I guess I should not be surprised, given my line of work, that as the season changes from summer to fall a lot of folks will open a conversation with me by asking for my predictions for the winter ahead.
Well I suppose that is fair enough. Truth is the snow gods have not been so generous the last couple of winters so snow lovers are understandably nervous about the coming winter.
Humans have been trying for some time to do long term forecasting. Think back to the Farmers Almanac with it’s predictive methodology cloaked in secrecy and even mysticism. What is their secret formula? Pig livers or something?! Well modern seasonal forecasting is a lot more scientific and open about it’s methodology. The science has advanced to the point where the skill with which it predicts is comparable to a 6-8 day weather forecast: it’s better than random guessing, but not quite something you can bank on.
So before we start to make conclusive statements about how the winter ahead will be, let’s take a brief look at what the predictive skill of these seasonal forecasts actually is.
Seasonal forecasts work primarily by following the development of slow moving patterns of ocean temperature and then linking these with historical changes in global weather. It’s a bit like how big box stores predict you’re life situation by examining your buying habits: The ocean/atmosphere relationships may have predictive value when viewed from the perspective of understood theories of how heat and moisture move around the earth over a time frame of weeks to months.
The International Research Institute for Climate and Society at Columbia University describes the predictive skill of these models this way:
“Forecasts of the likelihood of enhanced or suppressed rainfall, or lower or higher temperatures than the average, over the course of a season have a level of accuracy that is far from perfect but noticeably above the level of random chance”
If you’re interested in seeing a statistically based and very graphic representation of the predictive skill of the seasonal forecast system at Environment Canada check this out.
This tool basically looks at the percentage of the time that seasonal forecasts were accurate in the past. Play with it a little by entering different lead times, different times of year and either temperature or precipitation. What you’ll find for example is that with a three month lead time for an autumn forecast (Sep/Oct/Nov) of temperatures, these forecasts historically have have been correct about 55% of the time for Vancouver Island. On the six month time frame that percentage drops to a 0-40% range.
So for sure, sea surface temperatures are above “historical norms” at present and this could well mean that we are in for a warmer autumn than these historical norms. But the fact is that climate is a varied and complex thing and it's only September as I write!
I’ve been an avalanche forecaster for long enough to know how often we can get things wrong and how wrong we can get them! So what is my message? Well simply stated: don’t get your knickers all in a twist about another terrible winter lying ahead of us. Recognize that while the predictors are suggesting the possibility of warmer temperatures this autumn, that really does not say much about what our winter will look like.
Environment Canada meteoroligist Matthew MacDonald (who is also a keen backcountry skier and works with our professional avalanche association) had this to say in a recent discussion with me on this subject:
“What we can tell you is that strong El Niño’s typically result in warmer than normal winters on the west coast and slightly drier than normal conditions. Does this mean it won’t snow at Mt Washington this winter? No. Does this mean we won’t see an Arctic Outbreak this winter? No. All it means is that once we get to April 2016 and look back on the previous 3 months’ worth of weather, the average 3 month temperature will likely have been warmer than normal.”
A colleague of Matt's who also does lots of work for the avalanche industry, David Jones, wrote an informative, critical and funny paper on this subject called “The Cold, Dry and Bitter Truth about Seasonal Forecasts”. From the title you can guess that David is also wanting to shed some light of reality onto seasonal forecasting. You can download that paper here.
If you find all this interesting and want to dig deeper, in addition to resources we’ve mentioned above, here are some other resources for you:
A tutorial called “The Science and Practice of Seasonal Climate Forecasting” can be found at the International Research Institute for Climate and Society web site here.
If you are interested in a .pdf file of the current “Environment Canada Integrated Seasonal Climate Bulletin” send us an email and we can send you a copy of that document.
Here at Island Alpine Guides we are as excited for winter as ever and can’t wait to get on our skis and snowboards! As always, we’ll have our team of the island’s most experienced mountain professionals ready to get you out into the snow. This winter we’ll continue to offer our range of excellent Avalanche Skills Trainings and Tours. In addition we’re really excited to be rolling out the island’s first ever Hut Based Touring and are stoked for the return of the Women’s Backcountry Weekend. We’ve just started to put dates up on the web site for the coming winter and are keen to hear from you if you have specific dates that you’d like to see particular programs happening on. So check out the web site and get in touch to let us know what you want to do in the snow this winter.
Now go kick it old school and throw some skis on a bonfire for Ullr and we’ll see you in the snow!
Jan and the team at Island Alpine Guides