Backcountry skills中文
Avalanche Basics: Forecast, Terrain, Snowpack, and Decision Boundaries
An avalanche is terrain, snowpack, weather and human decisions acting together. Without a course, a partner and rescue gear, stay out of avalanche terrain.
In short
Before entering avalanche terrain, do three things: read the local avalanche forecast for the danger rating and the problem type, read the terrain for slope angle, aspect and traps, and read the recent weather history. Carry a transceiver, probe and shovel, know how to search with them, and never travel alone. If the forecast is high or extreme, change the route or stay home.
Avalanches are not random. They are the output of four inputs — terrain, snowpack, weather and the decisions people make — and three of those can be read before you leave the car.
The three checks
- Forecast. Read the local avalanche forecast before departure: the danger rating, the problem type (new snow, wind slab, wet snow, deep persistent slab), and which aspects and elevations are dangerous.
- Terrain. Slope angle, aspect, runout and terrain traps — gullies, cliffs, timber. "It doesn't look steep" is how people end up on a 35-degree loaded slope.
- Snowpack. Recent snow and wind, temperature, rain, freeze-thaw. If you cannot dig and interpret a snowpit, do not judge stability yourself.
Gear and partners
- The trio: transceiver, probe, shovel. Own them, carry them, and be able to search and dig with them.
- A helmet and an airbag pack are supplements, not immunity. Do not go solo.
- Run a beacon check before starting, agree the search and evacuation plan, and never use the gear for the first time in a real accident.
Decision boundaries
- Forecast at high or extreme, recent incidents, obvious wind slabs or wet-snow activity: change the route or do not go.
- Unfamiliar aspect or elevation, no alternative route, a narrow weather window: be conservative.
- Anyone in the group without gear, without training, or unwilling to turn around on plan: lower the objective.
- Technical terrain — glaciers, steep snow, roped travel — needs a course and a guide, and is outside this article.
Common mistakes
- Concluding the snowpack is stable because "it hasn't snowed lately".
- Carrying the full kit without knowing how to search.
- Sending one person down first with nobody watching from a safe point.
- Treating "someone skied it" as evidence of stability.