|Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
|Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
|Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.
|Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
|Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
|Likelihood of Avalanches
|Natural and human-triggered avalanches unlikely.
|Natural avalanches unlikely; human-triggered avalanches possible.
|Natural avalanches possible; human-triggered avalanches likely.
|Natural avalanches likely; human-triggered avalanches very likely.
|Natural and human-triggered avalanches certain.
|Avalanche Size and Distribution
|Small avalanches in isolated areas or extreme terrain.
|Small avalanches in specific areas; or large avalanches in isolated areas.
|Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.
|Large avalanches in many areas; or very large avalanches in specific areas.
|Very large avalanches in many areas.
One recent natural dry loose avalanche was observed at upper elevation on 12/7. There are likely more from the 12/8 storm, but we were unable to document due to poor light conditions yesterday.
|Size (D scale)
|Unlikely to bury a person
|Can bury a person
|Can destroy a house
|4 & 5
|Can destroy part or all of a village
Two back-to-back storms, 12/6-7 and 12/8 brought approximately 8-10″ of new low-density snow. The new snow has landed on a mix of hard surfaces, rain crusts up to 3500’, and softer old snow.
Storm snow totals vary by area and not necessarily by elevation. While the Frosty Bottom Snotel (2700′) reports 2-3″ of snow in the last 24 hours, we observed 6″ of new snow at 1200′ and 3″ at about 3000′ in the Independence Mine parking lot, and 2″ near Lucky Shot Mine (Willow side) over the last 24 hours.
Where the new snow sits on firm surfaces and rains crusts, dry loose avalanches will be more likely to trigger.
Even a small loose dry avalanche may be able to sweep you off your feet and carry you into other hazards.
Small dry loose avalanches can be mitigated safely with appropriate slope cutting techniques.