Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
Over the past month, new weak layers (facets and/or crusts, and occasionally surface hoar) have formed in the upper portion of the snowpack. In response to seemingly continuous new snow and wind, these layers have produced several avalanches over the past two weeks (Dollarhide, Galena Summit, Smiley Creek, Beaver Creek, Sawtooths, Banner Summit). With yesterday's storm adding yet more weight, triggering an avalanche breaking in the top 3' of the snowpack will be more likely today—and don't forget that we still have weak snow near the base of the snowpack.
What you shouldn't do: attempt to overthink/outsmart the problem. These weak layers present a complicated scenario, and even professionals are struggling to identify patterns. Some of the new weak layers have already produced avalanches, but others have yet to show their hand.
What you should do: take a step back and take a more holistic view. Recent loading due to new snow and wind? Check. Weak layers in the snowpack? Check. Recent avalanches? Check. When you look at it that way, the situation becomes more clear. Adopt the K.I.S.S. principle when choosing the terrain to play in: Keep It Simple & Safe. Triggering an avalanche will be most likely on upper elevation slopes steeper than about 35 degrees. Excellent skiing and riding conditions exist, and you can enjoy the new snow in a relatively safe manner on moderate slope angles on mid-elevation slopes sheltered from the wind.
The top 3' of the snowpack contains a number of weak layers that have formed over the past month.