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.
