The United States and Canada utilize the same five-category avalanche danger estimation scale. The tool is used by avalanche forecasters to broadcast the daily potential for avalanches in a given area. If you enter avalanche terrain, your safety depends on your ability to understand and assess conditions on the slopes you plan to climb or descend. Learning to read the avalanche danger scale is an excellent step toward backcountry preparation.
Avalanche terrain is often defined as a snow-covered slope steeper than thirty degrees, but it extends to any terrain beneath the slopes. Therefore, if a ravine toward the peak of a mountain is more than thirty degrees in steepness, the entire area below this drop is considered to be avalanche terrain.
North American Avalanche Scale
The North American Avalanche Scale consists of five ascending danger levels which provide travel advice and a means of planning your day—whether it should eliminate certain areas of a range, change mountains altogether, or stay inside. The assigned avalanche danger applies only to avalanche terrain, but designations can apply to large areas. It is therefore your job to make slope-specific assessments.
Low avalanche danger, characterized by a green check-mark, does not mean an absence of danger. Rather, it is meant to communicate that there may be loose snow on isolated features of a particular area. Moderate danger signifies the need to carefully evaluate snow and terrain with heightened caution; you should avoid areas of terrain identified in the day’s safety report. Considerable danger means you should avoid avalanche terrain if you do not have the skills or experience to move carefully through the area; human-triggered avalanches are likely. High avalanche danger signals that, regardless of your experience, you should avoid all avalanche terrain. Your safe options within the terrain become limited to non-existent.
Below, we have included an infographic provided by Avalanche.Org.