Sherwin Ridge: Stubborn Wind Slabs and Persistent Weak Layers

SNOWPACK OBSERVATION
Submission Info
Forecaster
Thursday, January 11, 2018 - 9:00am
Red Flags: 
Recent loading by new snow, wind, or rain
37° 36' 43.2" N, 118° 59' 31.2" W
Snowpit Observations
More detailed information about the snowpack: 

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.

Snowpack photos: 
Layers that failed during testing today.
Weather Observations
Blowing Snow: 
Air temperature: 
Wind Speed: 
Precipitation: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

ESAC receives support from ...