Quick report
The focus for today was to assess the wind slab problem at mid and upper elevations. Since we found little evidence of Wind Slabs, we did a welfare check on our December weak layers (12/7 and 12/18).
- We found pockets of wind slab (< 4" thick) and wind crusts near ridgelines.They were unreactive to our weight.
- Snowpits on north and south aspects showed well-consolidated, stable snowpack with potential future weak layers near the surface.
- We were surprised to find the 12/18 and 12/7 layers still contain large and well-preserved depth hoar and surface hoar grains mixed with smaller, rounding facets. In 3 of 4 tests, these layers did not fail. See snowpack section.
- The primary concern for future loading is the squences of hard crusts and facet layers in the top 8" of the snowpack.
- A sun crust dominated southerly surfaces and a rime crust about 4" below the snow surface existed above 6500' on all aspects.
- Dusting of fresh snow overnight with some large, flat surface hoar crystals on primarily south and west aspects.
- Slight warming as the day progressed. We did not experience a rapid drop in temperatures. Skiing was pleasant, in a lot of layers.
- We saw yet another glide crack to add to the region's collection on a southerly aspect at 5800'.
Weather
- Air Temp
- 10
- Cloud Cover
- few
- Wind Loading
- none
- Recent Snowfall
- 2
- Snow Avail For Transport
- small smounts
Calm below ridgelines. Light but cold NE winds at upper elevations with mostly clear skies and sunshine. Towards mid afternoon, some clouds built in for broken skies and S-1 snowfall.
Snowpack
- Southerly Aspect at 7000 ft, HS = 150cm
- Right-side up snowpack, mostly 1F hard.
- Primary concern is in the near-surface layers, which consist of a 10-12 cm thick sequence of two crusts above two layers of soft, weak facets.
- In tests, the facets fractured easily but did not propagate. ECTN4 down 10cm at crust/facet interface.
- At 70cm down, we found a thin layer of striated depth hoar and facets (up to 10mm) above a P-hard crust (likely the 12/18). Performed deep tap test with results of DTN.
- Northerly Aspect at 6800 ft, HS=160cm
- Again, a right-side up snowpack but softer.
- Take away was again the potential weak layers in the near-surface snowpack. Again, a 10-12 cm thick sequence of crusts and facets. The lower crust here was a thin rime crust.
- ECTN23 down 40cm on a storm interface.
- At 80cm down, we found the 12/18 surface hoar layer. Some grains were well-preserved and very large, (up to 20mm), but lying flat and not upright. Mixed with smaller facets. A Deep tap test produced a very clean planar shear with hard force (DT21 SP).
- Both profiles dug to about 100 cm below the surface.