Natural avalanches are unlikely, but human-triggered avalanches are possible. Caution should be exercised on steep terrain. High probability of unstable slabs on steeper slopes. Natural avalanches are possible, and human-triggered avalanches are likely. Caution must be exercised on steep terrain.
Unstable slabs are likely on moderate and steep slopes.
Natural and human-triggered avalanches are certain. Extreme caution and avalanche awareness skills must be used for safe travel on avalanche terrain. Extremely unstable slabs are certain on most slopes. Frequent natural and human-triggered avalanches are certain, and can be extremely large and destructive. Travel is strongly not recommended on or below avalanche terrain.