U.S. Urban Avalanche Danger Scale |
| Danger Level & Color |
Avalanche Probability & Avalanche Trigger |
Degree & Distribution of Avalanche Danger |
Recommended Action in Developed Areas |
Recommended Action in the Backcountry |
| WHAT |
WHY |
WHERE |
WHAT TO DO URBAN |
WHAT TO DO BACKCOUNTRY |
| LOW (GREEN) |
Natural avalanches very unlikely. Human triggered avalanches unlikely. |
Generally stable snow. Isolated areas of instability. |
Normal caution is advised. |
Travel is generally safe. Normal caution is advised. |
| MODERATE (YELLOW) |
Natural avalanches unlikely, potentially destructive avalanches unlikely to come near or reach developed areas. Human triggered avalanches possible. |
Unstable slabs possible on steep terrain. |
Use caution in or under steeper terrain and in avalanche zones. |
Use caution in steeper terrain on certain aspects (defined in accompanying statement). |
| CONSIDERABLE (ORANGE) |
Natural avalanches possible, potentially destructive avalanches may come near or reach developed areas. Human triggered avalanches probable. |
Unstable slabs probable on steep terrain. |
Be increasingly cautious in or under steeper terrain and in avalanche zones. Monitor avalanche forecasts. |
Be increasingly cautious in steeper terrain. |
| HIGH (RED) |
Potentially destructive natural avalanches likely to come near or reach developed areas, natural and human triggered avalanches likely. |
Unstable slabs likely on a variety of aspects and slope angles. |
Being in avalanche terrain or avalanche zones is not recommended. Minimize exposure time in avalanche zones. Monitor avalanche forecasts. |
Travel in avalanche terrain is not recommended. Safest travel on windward ridges of lower angle slopes without steep terrain above. |
| EXTREME (BLACK) |
Potentially destructive natural avalanches likely to reach developed areas. Widespread natural or human triggered avalanches certain. |
Extremely unstable slabs certain on most aspects and slope angles. Large, destructive avalanches possible. |
Being near or in avalanche terrain or avalanche zones is not recommended. Eliminate exposure to avalanche zones. |
Travel in avalanche terrain should be avoided and travel confined to low angle terrain well away from avalanche path run-outs. |
