Weather and snow observations station, Cheget, Russia.
"I have no data yet," said Holmes to Watson at the beginning of the "Scandal in Bohemia" case. "It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts."
Sir Arthur Conan Doyle
4 question summary
- Is the snow stable?
- Could the slope produce an avalanche?
- What are the consequences?
- Will conditions get better or worse?
The four question summary is a check list approach to help decision making before venturing out for the day or onto a particular slope.
The answer to each question is found by investigating and assessing a wide range of factors known to contribute to avalanche hazard. There is no single test or piece of information that can give a definitive answer. The evaluation and forecasting of avalanche hazard is an art rather than a technique, and must be learned through practice and experience. (M. Diggins and B. Barton 2001).
1. Is the snow stable?
To get an idea of the snow stability you need to start gathering 'clues' as soon as the day begins. Contact a local avalanche hazard advisory. Call someone who knows the area. What is the weather doing? Which way is the wind coming from? Are their signs of recent avalanches? - Natural avalanche activity is a sure sign of instability.
Follow the US National Avalanche Centre's: A Day in the Backcountry step by step tour for tips and tricks on gathering snow stability information.
2. Could the slope produce an avalanche?
We know that 35 to 45 degrees is the angle at which slab avalanches most often occur. It is also necessary to look at localised terrain features. Where are potential start zones? Be aware of what is above and below the slope you are on.
3. What are the consequences?
If you must travel across avalanche terrain, be mindful of the consequences if an avalanche does occur. What is the likely size of the avalanche? Where are the escape routes? Are their terrain traps - cliffs, crevasses, rock out-crops, a narrow gully . . . that could compound the seriousness of an avalanche and the amount of snow that could bury you.
Follow safe travel techniques:
- Only expose one person at a time to the hazardous slope.
- Wear releaseable bindings (skiers).
- Keep your pole and axe straps off your wrist.
- Move from safe spot to safe spot.
- Never travel above another person.
- Always move a safe distance away from the base of a slope that you just descended.
- Watch your partners and signal when you are clear of the slope.
4. Will conditions get better or worse?
Hazard evaluation is an ongoing process. Clues must be collected continuously, and the evaluation and forecast upgraded with every new piece of information. Changes in weather: temperature, wind speed and direction and precipitation rates can be significant.
To test out your decision making skills try out the US National Avalanche Centre's: Interactive Backcountry Tour.