Continued Persistent Slab Concern

Observations were made in the Fireplug area to see if the buried faceted layer will be a potential problem with the upcoming storm.  At 2 different sites, snowpack tests were done.  At upper site:  9080', N39.325447 W-119.904084, N aspect.  A shallow snowpack existed with snowpack tests showing no results on the faceted layer mid pack.  This area was thought to have been exposed to previous wind scouring by a Dec. NE wind event that removed the near surface facets that are buried in other locations and the cause of our persistent slab problem . 

At lower elevation site:  8880', N39.327111 W-119.905093, N aspect.  CT's were showing sudden collapse results and 2x PST's were 35/100 END and 37/100 END in the buried facet layer-see video.  2x ECTN's.    This site was in below treeline terrain and had more protection from previous NE wind events with a more developed buried facet layer. 

Isolated areas continue to show the possibility of a persistent slab avalanche problem as this buried facet layer is increasingly stressed by additional storm load.  Pre storm this morning, this weak layer was unlikely to fail as an avalanche, as indicated by the ECTN results not showing propagation.  However, the PST results indicate that propagation is likely if failure can be initiated.  Initiating failure will become easier and increasingly likely as load from accumulating storm snow adds stress to the weak layer. Concern continues for steep, open areas in near treeline and below treeline terrain on NW-N-NE aspects, especially with fair to good NE wind protection.