Sherwin Ridge: Stubborn Wind Slabs and Persistent Weak Layers

Toured over rocks and bushes up behind Mammoth Rock to look at sensitivity of wind slabs and persistent weak layers. Very warm with light W winds on the way up. Snow glopping onto my skins. Kick tests behind Mammoth Rock had no results. Snow surface was generally a thin, 2-7cm thick, wind slab that was moist and 4F to P hard on top of dry, F hard precip particles. Snow depth ranged from 30 to 90cm. Several hand shears failed easily down 35cm on a F hard facet layer (large facets: 3mm) under the rain crust that was buried on 1/6. Test snowpit on a NNE 34 degree slope at 9500' had several failures: CTE SC x2 down 7cm at the interface between new wind slab and storm snow, CTM SP x2 down 43cm at the interface between the 1/6 rain crust and the 1/4 facets (facets were very large and well developed, also getting wet), CTH SC x2 down 65cm on F- hard large basal facets under 1F- hard facets, ECTN 9 under the wind slab at 7cm down, ECTP 20 in the 1/4 facet layer 43cm down (see snowpack photo). Snow depth at this location was 78cm.

Got to the top of the ridge (10,000') around 930am. Moderate S winds with strong gusts. Still quite warm: Tair= 1 deg. C. Ski pen= 4cm, Boot pen= 30cm. No blowing snow seen anywhere on the Sherwins or the Mammoth Crest. No visible recent avalanches anywhere. Stomped on a lot of cornices and steep wind loaded slopes at the top of the Hose: no results, only localized cracking. Ski cuts had no results.