Hazard rating definition table

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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