Avalanche Problem

An example of an avalanche problem from the public avalanche forecast. In this case a persistent slab problem exists at all elevations and aspects. The chance of an avalanche is between possible and likely and the expected size is between 2 and 3.5. We are also warned of three weak layers recently responsible for some very large avalanches. All told, this represents a very significant hazard to the mountain traveller; safe travel will require careful route selection.

Avalanche problems are eight types of snowpack instabilities commonly encountered in the mountains and referenced in avalanche forecasts. They are diverse and include instabilities such as persistent slabs and wind slabs. Some characteristics and management strategies are shared between problems while others are more specific to particular problems. The eight problems are:

  • Storm slab
  • Wind slab
  • Wet slab avalanches
  • Persistent slab
  • Deep persistent slab
  • Loose dry avalanches
  • Loose wet avalanches
  • Cornices

Avalanche Canada’s daily forecasts discuss up to three avalanche problems, in decreasing order of concern. The forecast will indicate where each problem might be found (elevation and aspect), the likelihood of triggering or being exposed to an avalanche, and the size of avalanche expected if triggered. By understanding what kind of avalanche danger is present and what kind of terrain it can be found in, you can better match your terrain choices with avalanche conditions.