Weak snowpack structure below tree line in the Lakes Basin

Submission Info
Volunteer Observer
Thursday, December 24, 2020 - 10:00am
37° 35' 53.2788" N, 119° 0' 10.9692" W
Snowpit Observations
More detailed information about the snowpack: 

Went for a tour below tree line in the lakes basin to check out the lower snowpack structure on a variety of aspects.  Found a similar structure as has been described elsewhere in the Mammoth Lakes area- some soft settled snow on top of a stiffening slab of December storm snow over November facets with a decomposing crust in the middle on WNW through NE aspects between 9000’ and 9300’.  The very bottom of the pack in this area below the facets appeared to be ~10cm of 1F to 1F+ rounds.  I did not travel on E through SW.  I got on one due W slightly wind stripped area and found a shallow snowpack, <30cm, with a series of sun crusts, but no loose facets.  I did not find any buried windboard as had been reported higher up towards the Mammoth Crest.  The very strong SW winds on 12/21/20 did not move too much snow around down there in the trees, but some ski tracks were partially blown in.  

Extended column tests consistently showed propagating results failing on/in the weak facet layers, but at a variety of interfaces.  On WNW 22-degrees slope at 9100’, one test initially failed in the middle of the facet layer below the slab, but the propagated along the interface (ECTP15) and another initiated below the mentioned decomposing curst and also propagated along the slab-facet interface (ECTP22) (see pit profile and photo).  Both tests had positive results, but they didn't feel like they had much energy or pop to them.  On a NE 28-degree slope at ~9250’, fracture initiated and propagated below the decomposing crust (see pit profile and photo).  No collapses, whumphs, or shooting cracks while traveling.  

Snowpit or crown profile photo or graph: 
Weather Observations
More detailed information about the weather: 

Overcast morning with some light W winds developing with moderate gusts by 9am.  

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