Mammoth Crest: Persistent Weak Layers, Small Wind Slabs

Submission Info
Wednesday, February 28, 2018 - 12:30pm
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Snowpit Observations
More detailed information about the snowpack: 

Toured up behind Lake Mary to near Hammil Lakes and traversed SE just under the Mammoth Crest at about 10,000' looking for and testing the persistent weak layers in the upper 1/3 of the snowpack in advance of the big storm heading our way this weekend.

The facet layer was observed on specific sheltered slopes between 9200' and 10,000' on N and NE aspect buried down between 40 and 60cm. It is generally just below an old melt-freeze crust that ranges from thin hard ice to 1F hard and breakable. These facets were between 1.5mm and 3mm in size. Hand shears that cut down through the crust above failed with easy force in the facet layer. Test profile dug on a N aspect at 10,000' had sudden planar small column results and ECTP results in this facet layer which was 56cm down locally. See attached profile and photo of ECT results.

In open areas that have been exposed to the wind any buried facets lay under a thick (15cm+) 1F to P hard old wind board which has wind broken snow on top. Also noted some isolated areas of occasional wind transport from S winds and isolated small new wind slabs that gave me very small kick test results (see attached videos of wind transport and kick test). The wind was gradually picking up and by the time I got to the Emerald Lake Trail at 2pm S winds were visibly loading the top of Hammil Bowl. Areas of blowing snow from S winds were visible above treeline on the Sherwins and Laurel Mtn on my drive home.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
ECTP22 SC test results down 56cm in 1.5mm facets
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 
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