U.S. Avalanche Danger Scale

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These descriptions for the following danger ratings are the proposed, North American versions we will all use during the 2009-10 season.

 

 

 

 

 

 


No danger ratings have been issued for this area, but general information is available in the bulletin.
  

Generally safe avalanche conditions.  Watch for unstable snow on isolated terrain features.
 
   

Dangerous avalanche conditions on some terrain features. Evaluate the snow and terrain carefully and use good travel habits.
   
 
Dangerous avalanche conditions.  Use conservative decision making, careful route finding, and good travel habits.  Training and experience are essential.
   
 
Very dangerous conditions.  Travel in avalanche terrain is not recommended.  Extensive skill, experience, and local knowledge are essential.
   

Avoid all avalanche terrain. Travel only on gentle slopes well away from areas affected by avalanches.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

The following are the old descriptors for danger ratings in the U.S.

 

Danger Level
(& Color)

 Avalanche Probability and Avalanche Trigger Degree and Distribution of Avalanche Danger Recommended Action
in the Backcountry
...WHAT... ...WHY... ...WHERE... ...WHAT TO DO...

(GREEN)
 Natural avalanches very unlikely. Human triggered avalanches unlikely Generally stable snow. Isolated areas of instability. Travel is generally safe. Normal caution is advised.
 

(YELLOW)
 
 Natural avalanches unlikely. Human triggered avalanches possible. Unstable slabs possible on steep terrain. Use caution in steeper terrain on certain aspects (defined in accompanying statement).
 

(ORANGE)
 
 Natural avalanches possible. Human triggered avalanches probable. Unstable slabs probable on steep terrain. Be increasingly cautious in steeper terrain.
 

(RED)
 
 Natural and human triggered avalanches likely. Unstable slabs likely on a variety of aspects and slope angles. Travel in avalanche terrain is not recommended. Safest travel on windward ridges of lower angle slopes without steeper terrain above.
 

(BLACK)
 
 Widespread natural or human triggered avalanches certain. Extremely unstable slabs certain on most aspects and slope angles. Large, destructive avalanches possible. Travel in avalanche terrain should be avoided and travel confined to low angle terrain well away from avalanche path run-outs.

 

 

 

 

Avalanche Safety Basics

Avalanches don't happen by accident, and most human involvement is a matter of choice, not chance. Most avalanche accidents are caused by slab avalanches which are triggered by the victim or a member of the victim's party. However, any avalanche may cause injury or death and even small slides may be dangerous. Hence, always practice safe route finding skills, be aware of changing conditions, and carry avalanche rescue gear. Learn and apply avalanche terrain analysis and snow stability evaluation techniques to help minimize your risk. Remember that avalanche danger rating levels are only general guidelines. Distinctions between geographic areas, elevations, slope aspects and slope angles are approximate and transition zones between dangers exist. No matter what the current avalanche danger there are avalanche-safe areas in the mountains.

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