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Knowledge about potential avalanche starting locations is very useful for route planning. Avalanches are more likely where the snow is under tensile stress; this can occur due to convex slope curvature, uneven snow depth and anchor points on a slope. Where the terrain above the anchor point is more than 40 degrees snow will slough off the slope putting more load on the snow below.
Avalanche from toe of cliffs in Tignes
Grass provides an ideal sliding surface for snow. Willows and slide alder tend to stabilize snow early in the season, but later on, due to creep of the snow cover, are bent over until they are lying parallel to the ground, thus becoming a much less effective barrier. In cold, dry climates, the air spaces provided by brushy ground cover like willows and alder allow the development of large depth hoar crystals that provide a weak layer at the bottom of the snow pack.
Light timber, defined as timber which you can ski through without too much difficulty, is no protection; slabs can form from wind eddies ... Heavy timber, that is virtually impossible to ski through, is usually safe although abnormally large avalanches may break through from above.
