Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
On some "solar" slopes - particularly those facing east and southeast - there exists a persistent weak layer (PWL) of facets just above a crust which was buried by storms beginning February 14. Mark Staples's photo below shows this structure which can be found about 3' below the snow surface. The reactivity of this layer varies from one slope to the next, but it is possible Thursday's large avalanche in Mary Ellen Gulch may have failed on this layer. With many large cornices on many ridgelines, any natural or human-triggered cornice fall may trigger an avalanche failing on this PWL.
I'm handling this problem by avoiding it and heading to northerly facing slopes where the snow quality is superior and this avalanche problem doesn't exist.