Technical information, news, research, and opinion on avalanches, snow safety, and winter backcountry travel.

Tuesday, November 10, 2009

Elements Of Backcountry Avalanche Forecasting

Desire is the root of all suffering—the Buddha

NOTE: This post was updated on October 20th, 2010.

This discussion provides an intentionally brief outline of a skeletal framework for backcountry avalanche forecasting, along with some framing elements to help organise your thoughts. Remember, backcountry avalanche forecasting is just one technique out of a constellation of techniques that are useful for planning and traveling. For the purposes of this discussion, backcountry avalanche forecasting includes the decisions that are connected to the forecast.

The Elements Of Backcountry Avalanche Forecasting
Safe winter backcountry travel requires you to consider the current avalanche forecast during trip planning, and may require you to develop one or more on-site avalanche forecasts during the trip itself. Developing your own forecasts in the field is type of travel technique referred to as backcountry avalanche forecasting, and it is an essential element of safe route selection whether you're going up or coming down.

The following list combines several elements of avalanche forecasting as outlined by The Avalanche Handbook with a few thematic elements derived from some of my other work. The idea is to present backcountry avalanche forecasting in human-compatible terms using human elements that are highly related to decision-making in avalanche terrain. These elements are applicable before, during, and after a backcountry outing.
  • Goal. Align your perception of instability with reality.
  • People. Manage thoughts, actions, and beliefs that could affect the forecast.
  • Awareness. Maintain awareness of instability by observing terrain, snowpack, and weather.
  • Uncertainty. Acknowledge, identify, and reduce uncertainty to make safer decisions.
The elements of backcountry avalanche forecasting are framed around safety and provide tools that help you manage exposure and measure risk. The CAA defines risk as unacceptable if there is a significant chance of triggering a size 2 avalanche ( an avalanche large enough to bury, injure, or kill a person ).

Finally, before a brief explanation of each item, it is important to note that the elements of backcountry avalanche forecasting are interconnected. You cannot use any of these elements by themselves or errors will arise and lead to faulty or dangerous decisions.

The public avalanche bulletin provides good information about the distribution of instability across a large area, including information on aspects, specific snowpack concerns, and how changes in the weather might increase or decrease the amount of instability. Backcountry avalanche forecasting is not concerned with all the slopes in a mountain range, ski area, or highway corridor; backcountry avalanche forecasting is concerned only with forecasting instability for slopes that present a hazard during a backcountry outing. You cannot use a public avalanche bulletin to reach conclusions about instability on a specific slope because the spatial scale of the public avalanche bulletin is much larger than the spatial scale of a single slope. Therefore, to align your perception of instability with reality, you must combine the information from the public avalanche bulletin with accurate observations made at a specific time and place in the backcountry. In order to account for errors prior to decision-making, you must acknowledge that some degree of uncertainty exists, and you must integrate this uncertainty into your perception of instability.

Every human being has his or her own thoughts and beliefs that lead to actions. Positive qualities include priority, curiosity, honesty, humility, generosity, knowledge, and focus. Negative qualities include haste, disinterest, dishonesty, ego, greed, ignorance, and distraction. It is very important to maintain awareness of the self and of the group during any backcountry outing or these negative aspects will adversely affect the forecast. This includes outcomes such as not bothering develop a forecast in the first place, constructing a poor forecast from poor information, failing to realise that everyone is exhausted, or allowing fun and excitement to outshine awareness and uncertainty. Sometimes the best course of action is to suppress your personality and then proceed with a thoughtful evaluation of the human factors involved in the decision.

Maintaining awareness first involves realising that awareness is important, which is followed by teaching yourself how to pay attention. The second part involves learning how to observe the terrain, snowpack, and weather to maintain awareness of instability and the likelihood of avalanches. This includes instability tests, snow surface observations, and weather observations. Data sampling has an extremely strong influence on your beliefs about the presence of instability and its consequences, and like almost everything else in snow safety, data sampling can work for or against you. Mistakes in data sampling such as poor technique, inability to interpret the results, or lack of thoroughness, will lead to errors and bad decisions. It is very important to be extremely honest with yourself about your weather observation, snowpack assessment, and terrain evaluation skills or you will fail to improve and you will remain unaware. If you believe that your ability to collect information has been comprised, or if you believe the information itself may be compromised, it's best practise to throw away the data and make very conservative decisions.

Uncertainty is always present, but the amount of uncertainty is variable. High uncertainty is a sign that you lack the information—for whatever reason—required to make sound judgments about risk. This differs from normal uncertainty, which should not cause undue anxiety, nor lead to overly conservative decisions. When you're really not sure ( i.e. uncertainty is high ) then it's time to acquire more information or make conservative decisions. You must teach yourself to consciously acknowledge, identify, and reduce uncertainty if you wish to make safe decisions. Remember, if unaddressed, a highly uncertain mind is fertile ground for speculation, biases, and pseudo-scientific facts. ( Terrain selection is one of the best methods of managing uncertainty. ) Poor reactions to high uncertainty, including failure to acknowledge uncertainty, or failure to proactively manage uncertainty, are a direct cause of avalanche involvement in the backcountry.

This is a skeletal summary of backcountry avalanche forecasting. Being an exceptionally skilled backcountry avalanche forecaster may not be useful if you cannot read a map, use a compass, or if you possess poor first aid skills. This definition uses carefully selected terms to help shape and manage the learning process. Master as many planning and traveling techniques as possible.

The three primary sources of uncertainty are as follows:
  • Variations in human perception and estimation.
  • The spatial and temporal variability of the snowpack.
  • Incremental changes to the snowpack across space and time.

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