Mammoth Area -Sherwins-Snow Profile, Collapse in N Trees

SNOWPACK OBSERVATION
Murkwood
Submission Info
Forecaster
Tuesday, February 2, 2021 - 12:30pm
Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
37° 36' 30.3552" N, 118° 58' 9.6852" W
Snowpit Observations
More detailed information about the snowpack: 

The Sherwin ridgeline had two new avalanches, one above the bench on the perch at around 10000ft and another above the main avy path. Both avalanches were right adjacent to ridgeline on N-NE aspects and were from 1-3ft crown depth, 100-150 wide and running a short distance of 200vertical feet or so. They appeared to have occurred yesterday, likely in the afternoon with the significant wind load occurring. There was snow transporting today again being pushed by SW winds, but not as significant as the day prior.

I proceeded up to the Murkwood area to dig a snow profile in relation to investigating current structure/stability at a fairly similar location in regards to the recent skier triggered avalanche that occurred in Punta Bardini this past Saturday. I picked a slope of similar aspect ~22 NNE and was about 400ft lower in elevation (9357ft) to where the slide was triggered (9780ft). Basically at this location there was a robust 100cm slab now sitting on ~40cm of degraded weak old snow at the base.

The attached video explains my findings pretty well, but signs of instability I observed were a loud localized collapse around my snow pit when I took my first big shovel plunge into the old faceted snow at the base of the pack.  There was no cracking or avalanche related to this, but it was a bit spooky.

A CT25 Q1 failed at the new/old snow interface. Extended Column provided no results. Moderate to strong SW winds were blowing today with temperatures just below freezing. The top of Mammoth Mountain became enveloped by cloud late morning and the rest of the range became increasingly obscured by the next small storm front pushing in.

On the way up there was significant evidence of settlement in the snowpack and along the steep entrance into the north facing murkwood trees, there was evidence that there had been a widespread natural avalanche cycle initiating adjacent to ridgeline and piling up debris for a few hundred feet down slope on most trees. Couldn’t distinguish how deep the crowns had been.

 

Snow pit @ 9,357ft, 22 NNE Aspect, 36deg slope

HS: 140cm

CT25 Q2 @ 44cm

ECTX

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Snowpit videos (tests, etc): 
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