Hazard rating definition table

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Definition

North American Public Avalanche Danger Scale
Avalanche danger is determined by the likelihood, size and distribution of avalanches.


Danger Level Travel Advice Likelihood of Avalanches Avalanche Size and Distribution
5 Extreme Avoid all avalanche terrain Natural and human triggered avalanche certain. Large and very large avalanches in many areas.
4 High Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Natural avalanches likely; human-triggered avalanches very likely. Large avalanches in many areas; or very large avalanches in specific areas.
3 Considerable Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative desicion-making essential. Natural avalanche possible; human-triggered avalanches likely Small avalanches in many areas; or large avalanche in specific areas; or very large avalanches in isolated areas.
2 Moderate Heightended avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Natural avalanche unlikely; human-triggered avalanches possible Small avalanches in specific areas; or large avalanches in isolated areas
1 Low Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Natural and human-triggered avalanche unlikely. Small avalanches in isolated areas or extreme terrain.


Source: Statham, G., Haegeli, P., Birkeland, K. W., Greene, E., Israelson, C., Tremper, B., et al. (2010). The North American public avalanche danger scale. Paper presented at the International Snow Science Workshop, Lake Tahoe, CA. See http://www.avalanche.ca/cac/bulletins/danger-scale.

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