A look at near crust facets on Castle Peak.

A mix of soft unconsolidated recent storm snow, firm wind packed surfaces, and exposed rain crust were present on the S-SW-W-NW aspects traveled on Castle Peak today. Some minor amounts of blowing snow were noted, but no other informal signs of instability were observed.

A closer look was taken at facets above the Dec 15 rain crust as well as near surface facets on Castle Peak in the 8,500' to 8,900' range. Faceting was present in any areas on the aspects traveled where recent storm snow sat on top of the Dec 15 rain crust. In the current state, the weak layer and overlying slab did not yield any signs of instability in snowpit tests. This was changed by simulating new snow loading (see video and explanation below).

Video: At the snowpit site on a W aspect at 8,690', a loaded PST was performed using a method similar to the one presented by K. Birkeland and A. van Herwijnen in the Proceedings of the 2016 International Snow Science Workshop, Breckenridge, Colorado. Read the paper here. With the snowpack in a natural state, PST 70/100 end results and PST 20/100 SF results were obtained (Both of these results indicate propagation unlikely.). After building a form, 20 cm of disaggregated snow was added on top of the natural snowpack. The new artificial layer was allowed to sinter for 20 min to become a cohesive slab. PST results on the near crust facet layer directly on top of the Dec 15 rain crust changed to PST 25/100 end, indicating that with the additional load, propagation is likely to occur once weak layer failure is initiated. Density or extrapolated SWE of the artificial load was not measured as instrumentation was not available.