5.1.4 Avalanches
Avalanches form on slopes mild enough for snow to accumulate but steep enough for it to slide. Generally, this includes slopes between 30 and 45 degrees, although the slope threshold can be as steep as 60 degrees in maritime climates.
Every slope has a limit as to how deep the snowpack can be without sliding. That limit decreases as steepness increases, meaning that the steeper the slope, the less snowpack it can hold. If a slope is too steep, snow will not accumulate significantly so the slope will remain bare.
Different types of avalanches form depending on the characteristics of the snowpack. These include slab, point-release, slough, wet, and dry avalanches.
For more information on avalanches, please refer to other training materials, such as:
- COMET's Avalanche Forecasting module (publication expected in late 2010, see http://www.meted.ucar.edu/)
- The avalanche.org website (http://www.avalanche.org/)
- The Forest Service National Avalanche Center (http://www.fsavalanche.org/)