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

Monday, November 23, 2009

Perception Of Instability

She loves me, she loves me not—Unknown

NOTE: Backcountry avalanche forecasting is composed of four interconnected elements: goal, people, awareness, and uncertainty. The elements of instability are linked to awareness and uncertainty—maintaining awareness and managing uncertainty are central tools for helping people successfully accomplish the goal of backcountry avalanche forecasting.

The winter snowpack is stable most of the time, which is a state of existence referred to as conditional instability. This means it is possible to trigger avalanches under certain conditions, provided you discover a weakness and deliver enough energy to release an avalanche.

Figure 1.1. State of instability. Instability fluctuates between very stable and very unstable.
During conditional instability, weaknesses are not widespread, and the triggering energy is relatively high. Perception of instability is much poorer when the snowpack is mostly stable because it is very easy to become blind to instability. On the other hand, perception of instability is usually very good when instability is widespread and triggering energy is very low. Important questions are as follows:
  • What do I believe about the number of weaknesses and their locations?
  • What do I believe about the triggering energy required to release avalanches on these weaknesses?
  • Am I dealing with long-term weaknesses, short-term weaknesses, or some of each?
  • Am I at risk of making errors when weaknesses are rare?
  • Am I at risk of making errors when it may take a lot of triggering energy to release an avalanche?
To answer these questions, you have to start at the beginning, way back when your perception began to take shape.

The Origins Of Perception
This is a complicated subject, but it is important to realise that all of us have our own personal beliefs about the world around us. These ideas can influence our beliefs about snowpack instability and its consequences. Prior to a tour, you might review the public avalanche bulletin, or you might ask questions about local conditions on an Internet message board. You could also acquire information during the nightly weather report. Your perception of instability begins to take shape from the moment your brain begins to process relevant information. Similarly, taking an avalanche class may have a lifelong affect on perception of instability as a someone transitions from lack of awareness to awareness.

Your perception of instability is shaped whether or not you choose to manage the process. It's pretty easy to unconsciously form a perception of instability by reading the bulletin, talking to friends, and then making observations during a backcountry outing. However, it's much more useful to be consciously aware of what and how certain factors shape your perception of instability, and how this could affect your choices.

It's critical to remember that information of any kind can be helpful or harmful with respect to your beliefs about the presence and distribution of instability in the snowpack. This includes snowpack tests and weather reports and the presence of other parties. It is up to you to manage how this information affects your perception. Ideally, this information should help align your beliefs about instability with reality.

If your perception of instability is faulty, you will unknowingly expose yourself to hazards against which you will have little protection. If you can't assess your perception of instability, or if you feel your perception may have been compromised, then it's time to make conservative decisions.

Assessing Your Beliefs
Ask yourself the following questions:
  • How does the public avalanche bulletin affect my beliefs about instability?
  • How does the information I obtain from the Internet affect my beliefs about instability?
  • How does seeing tracks on the snow, or seeing other groups of skiers, affect my beliefs about instability?
  • How do weather observations affect my beliefs about instability?
  • How do the results of instability tests affect my beliefs about instability?
  • How does terrain selection reflect my beliefs about instability?
  • Am I aware of which elements shape my perception?
  • Am I aware of how my perception of instability affects my choices?
If you're interested in an quick exercise, evaluate a few memorable days from the last few seasons. If you can remember, write down your perceptions of instability on those days and look for patterns. Are your beliefs fairly uniform regardless of the public avalanche bulletin? Are your beliefs all over the map? Is it possible to place too much weight on the public avalanche bulletin and not enough on your own observations?

Are Your Beliefs Accurate?
Assess your beliefs about weaknesses and triggering energy to shape your perception of instability. This begins with your beliefs in general, and includes how the public avalanche bulletin influences your beliefs, and the effects of data sampling in the field.

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