How do you feel about considerable? Are you one to stay inbounds and out of the backcountry, waiting for a lower rating to branch out? Or perhaps you're the type of person to say, "Well it's ONLY Considerable, after all it's not high." What if I told you that 51% of avalanche related deaths in Canada happen when the danger rating is at Considerable? Does that change your perspective?
Their's three reason why Considerable is such a problematic hazard rating; it's risk is subjective to each person, requires advance training to choose terrain and monitor the snowpack and finally, it often involves a low probability / high consequence scenario. These factors make navigating in the mountains during a Considerable hazard challenging.
During considerable, one red flag that may be mentioned in the bulletin is the presence of a persistent weak layer (PWL). This winter saw us dealing with a number of PWLs. The February 10th layer, which is being coined as the "Drought Layer", continues to get results in compression tests across BC. Perhaps more concerning, results from propagation saw tests are being described as having wide spread potential. Now the March 2nd layer is continuing to persistent, adding more complexity to our snowpack.
Why aren't we seeing massive avalanches? Well these layers are getting to the point where they are so deep, up to 2m in places, that it's becoming difficult to affect. Does that mean it's no longer a concern? Unfortunately the potential is still there, the probability may be low but the consequences are very high. When we find ourselves in a Low Probability / High Consequence (LP/HC) scenario we tend to gain confidence. Natural avalanches become unlikely, critical warning signs are no longer present, and the avalanche summary in the bulletin reports no recent activity. But no results aren't necessarily good results.
If we're using the Avaluator 2.0 decision making tool, (Which I recommend to all of my students) then our choice of terrain is quite clear. Looking at the card, if we have a considerable rating and a PWL then we have to give ourselves 2 points on the Avalanche Conditions score. If we want to stay in the green then the card restricts us to not checking off any points for the Terrain Characteristics score. What does that mean? We must stay on supported slopes under 30°, free of terrain traps, convexities and well away from avalanche run-outs.
Unfortunately as someone who enjoys steep skiing that's not what I like to hear. My personal assessment is that a Considerable avalanche hazard implies a significant enough risk, that I stay out of avalanche terrain. But now we come back to my original question; how do YOU feel about Considerable?
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