Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 3
Even though no avalanche activity has occurred on the Dec. 2 facets, some snowpit tests on northerly aspects above 9000 ft. continue to indicate that if this layer breaks the resulting fracture can propagate along the persistent weak layer. Variability associated with where this layer exists, how weak it is, and how continuous it is increases the uncertainty surrounding this avalanche problem. Digging a quick pit can tell whether or not the facets exist at a specific location, but that data may not apply to the next slope over or even to a different part of the same slope.
Variability plus uncertainty plus persistent slabs makes conservative terrain selection and decision making essential. While many people may get lucky on a slope, that does not mean everyone will. On slopes where this weak layer exists and is continuous enough, one trigger point is all it takes for a person to start a fracture that could result in a large dangerous avalanche. Before committing to a line on NW-N-NE aspects above 9000 ft. evaluate the snowpack, terrain, and consequences carefully. Remember that observations like slope cuts and previous tracks do not indicate stability when dealing with persistent slabs. A slope breaking to the ground often represents the only warning this avalanche problem gives. Avoiding areas where these layers might exist or sticking to lower angle slopes without steeper terrain above them are the only mitigation options for persistent slabs.
