June 17, 2013
Winter 2012 - 2013




Many avalanche accidents can be avoided by always following 3 simple actions:
1) Ride one at a time in avalanche terrain: Only expose one person at a time and watch your partners from a safe location out of the avalanche run out zone.

 2) Look for signs of unstable snow: Recent avalanches are nature's #1 clue of unstable snow and are the most definitive indication of stability on similar slopes. 3) Make sure everyone in the group carries avalanche rescue gear: It should be carried in a small backpack on your body not on your sled, and everyone should know how to use it.

Recipe for an Avalanche

Why are these important to understand? Change any one of them and you don't get an avalanche.

1) Terrain: The slope must be steeper than about 30 degrees. Slopes less than about 30 degrees are not steep enough to avalanche.

2) Snowpack: The snow must be unstable. Mountain snowpacks are a series of layers. Some layers are strong, and some are weak. The snowpack is unstable when a strong layer rest on top of a weak layer.

3) Trigger: Extra stress on the weak layer can cause it to collapse and produce an avalanche. A trigger could be additional weight from a snowmobile or simply more snow.
 
In the above diagram, the buried weak layer has collapsed and the overlying slab layer has fractured and avalanched.