Thinking strategically about travel in avalanche country
By Dave Zinn Avalanche Forecaster at the Gallatin National Forest Avalanche Center
I learned the basics of avalanche safety in several awareness level courses when I began dabbling in backcountry skiing. I understood that I needed to carry avalanche rescue equipment, travel with a partner, avoid a few notorious slopes and not get caught in an avalanche. When I added stability tests to the toolbox, I dug in the snow, looked at test results, scratched my head and asked the inevitable question, “Do I ski this slope now or not?”
I desired a clear “go” or “no go” answer from a hole dug in the side of the mountain. This, unfortunately, is something no snowpit can provide, and this way of thinking dangerously fails to consider the big picture. A better way to think about stability and terrain choice is to develop a strategic mindset combining the avalanche forecast, weather, recent avalanche activity, weak-layers of concern, red-flags and test results with unstable indicators trumping stable indicators. Consider the following mindsets for backcountry travel:
- Assessment: Watch for signs of instability and dig and test to develop knowledge about the snowpack structure while limiting exposure to avalanche terrain.
- Status Quo: A good strategy when current backcountry travel parameters are working well and no change is needed. Be careful not to unintentionally expand terrain choices. When persistent weak layers exist, this may result in long-term entrenchment and little change over extended periods.
- Stepping Back: New snow, wind or information necessitates more conservative terrain selection.
- Stepping Out: A prolonged period of inactivity, lack of loading and/or lack of persistent weak layers suggest that more challenging terrain may be safe after further assessment.
Based on your strategic mindset for the day, put available terrain into three categories: Green Light, Yellow Light and Red Light. Green Light terrain is good to go based on the general knowledge about prevailing avalanche conditions and can be utilized after minimal assessment. Yellow Light terrain should be okay based on the current conditions but requires more extensive field observations and tests to give you one more chance to turn around. Red Light terrain equates to no-go zones. Do not turn Red Light Terrain into Yellow Light Terrain while in the backcountry thus ignoring the strategy you carefully crafted before staring at that super sick powder run.
These categories may include specific slopes or general types or terrain. For example on one day, Red Light terrain could be steep runs on Beehive Peak or slopes above 35 degrees in alpine terrain exposed to wind-loading. On another day with higher danger, we could say that any slope under 25 degrees with no overhead hazard is Green Light terrain.
While a stability test can’t give you a “go” or “no-go” answer, developing a strategic mindset based on the big picture outlined above will set you on the path to making informed backcountry decisions. As far as interpreting your stability tests, an unstable stability test result means no-go. A stable result only means you haven’t found a reason to turn around yet. Using an instability test to prove stability is a dangerous habit.
Further Reading: Atkins, Roger, 2014: Yin, Yang, and You, Proceeding, International Snow Science Workshop, Banff, 2014. Dave Zinn has been with the Gallatin National Forest Avalanche Center since 2019 and has ten years of ski patrol experience at Bridger Bowl and the Yellowstone Club.
