Introduction | Avalanche

Introduction // Abstract

An example of the CAC's avalanche forecast breakdown

I am a skier. For me, like many other skiers and snowboarders, the natural progression of skiing is away from the resort and into the backcountry, where better snow and more challenging terrain can be accessed on foot or by snowmobile. Unfortunately, outside of ski resort boundaries, the inherent risks of skiing and snowboarding are compounded with objective hazards, especially avalanche hazard. Avalanches are rapidly moving masses of snow and ice, which range in size and destructive potential from small and completely harmless to large and powerful enough to destroy an entire village. Within the boundaries of ski resorts, avalanches are controlled by ski patrol and safety staff with the use of explosives, ski cutting, and other techniques. But outside of ski resorts, avalanches are a dangerous and real risk to backcountry travelers, and they are almost never easy to predict.

There are infinitely many factors that affect the likelihood of a slope to avalanche, including short- and long-term precipitation patterns, temperature and temperature history, solar warming, and wind speed and direction. Avalanches occur when some combination of these factors causes gravity to overcome the shear stress, friction, and cohesion holding a layer of snow to an inclined surface, which can be a layer of snow with different qualities. Because avalanches are such complex events, prediction is an imprecise science, but the causes of avalanches can be simplified into four main categories: loading due to snowfall, loading due to wind deposition, the weakening or existence of deep persistent layers, and the solar warming of the snowpack.

The Spearhead Range, which extends behind the Whistler-Blackcomb ski resort, sees tens of thousands of skier-visits each winter. The Canadian Avalanche Centre produces daily avalanche forecasts for the range, which combine forecasts for wind slabs, storm slabs, and persistent slabs into a general danger rating on a 5-point scale, as well as providing a breakdown of each individual avalanche hazard. For each of these hazards, the CAC forecast provides the likelihood of an avalanche, the expected size of an avalanche, and the slope aspects which are most affected by the hazard.

As of yet, this data is only available in the written/graphical format used by the CAC—it has yet to be visualized on a map. This project aims to take the information provided by the CAC for a given day and produce topographical maps featuring a danger rating for each of the three possible avalanche types, as well as a combined hazard map for general avalanche conditions on that day, as an experiment in identifying avalanche conditions given a trusted, reputable forecast like that produced by the CAC and topography. Essentially, this project aims to visualize the already available forecast, rather than to attempt to produce its own forecast, the way previous GIS projects have done.

This project will focus on the Spearhead Range because of the sheer volume of people who use the area. The Spearhead is one of the most popular backcountry destinations in the world, and so in the eventual future of this project, it will provide a good ground for testing the project's accuracy against real-world observations.

This project should come with the disclaimer that it has not been tested or proven by anyone, and should not be used as a guide for avalanche safety. Until this project is refined, extensively tested against observed conditions, and further research is conducted, this is nothing more than a proof of concept. No map produced from this project should be considered a definitive forecast, accurate to any degree, or anything but an interesting experiment in avalanche prediction. Decisions made in the backcountry should be done so based on real world observations, reputable forecasts such as those from the CAC, formal avalanche training, and experience.