North American Public Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches. The five steps below are the North American Public Avalanche Danger Scale, the scale behind every danger rating Avalog shows for a Canadian or United States region.
Extreme
5- Travel advice
- Avoid all avalanche terrain.
- Likelihood of avalanches
- Natural and human triggered avalanches certain.
- Avalanche size and distribution
- Large to very large avalanches in many areas.
High
4- Travel advice
- Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
- Likelihood of avalanches
- Natural avalanches likely; human-triggered avalanches very likely.
- Avalanche size and distribution
- Large avalanches in many areas; or very large avalanches in specific areas.
Considerable
3- Travel advice
- Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
- Likelihood of avalanches
- Natural avalanches possible; human-triggered avalanches likely.
- Avalanche size and distribution
- Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.
Moderate
2- Travel advice
- Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
- Likelihood of avalanches
- Natural avalanches unlikely; human-triggered avalanches possible.
- Avalanche size and distribution
- Small avalanches in specific areas; or large avalanches in isolated areas.
Low
1- Travel advice
- Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
- Likelihood of avalanches
- Natural and human-triggered avalanches unlikely.
- Avalanche size and distribution
- Small avalanches in isolated areas or extreme terrain.