The first official day of fall has just past and that means our days will start to get noticeably shorter and darker as we get closer to winter and the riding season. This weekend we expect an early season snowfall in most of the mountain regions across the province, with some areas receiving as much as 25-30 centimeters. If you’re a backcountry skier/snowboarder or snowshoer, this is the time to start paying attention to what is going on.
What should we make of the early snowfall? It certainly throws a wrench into the works for folks who were still hoping to get a few alpine hikes and mountain bike rides in, while others will be celebrating Ullr’s early arrival and the promise of a great winter season.
From an avalanche forecasting perspective, it means we should start to keep track of what happens next because there are a few different ways in which this snowfall could become problematic later this winter. The biggest problem with early season snowfall is that it is a (very) thin snowpack which is susceptible to either melting or weakening – or both.
If the temperatures stay cold and dry, we will see this thin snowpack start to become weaker as the snow starts to facet. With time the snow will consist primarily of large-grained facets. This will then sit at the base of the snowpack and once more snow arrives it becomes depth hoar. These types of layers take a long time to heal and sometimes never fully recover and are with us for the rest of the winter.
However, if we get a longer stretch of nice, warm and sunny fall weather, the early season snow will melt down to bare ground. It melts faster on sunny aspects but depending on freezing levels and temperatures even shaded aspects could be back down to bare ground. From an avalanche perspective this is probably our best scenario because it means that once the proper winter snowfall arrives, it will fall on bare ground.
If we get a bit of both we could end up with a melt-freeze crust above a weak layer of facets that then becomes buried by our winter snowpack. This in turn may mean ongoing persistent slab problems and eventually deep persistent slab problems. Not good. Luckily it is still only October so there is a reasonable chance we still have another warm spell or two before winter really sets in.
So what can we do from now until the start of winter? Mainly, we should monitor the snowpack and the weather. Keep track of the distribution of any potential future weak layers by keeping tabs on what elevation the snowline stays at and what the snow coverage is like on the different aspects as we get closer to winter. This will help you eliminate elevation bands and aspects that don’t have any snow left on it and shouldn’t be a concern for these particular problem layers going forward. Checking out webcams from highway passes and weather stations to gauge how warm it gets up in the alpine are some of the tools available to us from a distance.
In the meantime, this is a great time of year to take out your winter equipment and give it a once-over, double-check that your transceiver is functioning properly and that everything else is good to go. Industry professionals continue to work on their rescue skills year after year and run scenarios at the beginning of each season. Get outside and practice with your friends and touring partners to make sure everyone remembers what to do in case of an avalanche incident. No time like the present!