Tahoe National Forest Sierra Avalanche Center

Very thin melt freeze crust discontinuously present in this location.

Pit dug in open 30m x 70m area below treeline. PST performed at 50cm had fracture move up to 54 cm height for end propagation.

Test pit done in below treeline terrain to look at near crust facets on 12/15 rain crust. Layer details were not recorded.

Visited Ralston Peak to check out rider triggered avalanches from 12.26.16. Pit was dug in more East facing terrain on edge of Ralston Bowl than the more North facing slopes that slid. This was done to avoid exposing observers to the slope in question and potential hang fire. Facets above the extremely strong 12/15 rain crust were present in this location (PST 45/100 END).

Pit dug in shaded near treeline terrain.

Looking at upper snowpack as winter storm is arriving.

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 60 min. PST 40/100 END @ 120cm (just above the crust) and at the boundary between the added snow and the natural snow surface (156cm)

Pit dug in avalanche path, just below start zone.

Pit dug to look at NSF's and NCF's above the 12/15 rain crust. Multiple PST's showed either slab fracture or 70-100/100 END results. After artificially loading 20cm on top of surface snow we had a PST 25/100 END on NCF's above the 12/15 RC.

Put dug in open area below treeline with full shade this time of year.