September 8, 2010
Winter 2009 - 2010




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

There are 3 ingredients necessary to get 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.