Wind Slabs and Loose Wet on Red Cone

SNOWPACK OBSERVATION
Submission Info
Forecaster
Friday, April 20, 2018 - 4:00pm
Red Flags: 
Recent loading by new snow, wind, or rain
Rapid warming
37° 35' 43.08" N, 119° 1' 31.44" W
Snowpit Observations
More detailed information about the snowpack: 

The storm snow from the 16th was transitioning and rapidly warming today on top of the breakable 04/16 melt-freeze crust which was found down between 15 and 25cm below the surface on E-SE-S aspects where there was enough previous sun exposure for that crust to form. On sheltered northerly slopes above about 9500' there was no 04/16 MFcr and the recent storm snow was directly above the hard 04/11 melt-freeze layer which was down between 25 and 35cm and was found to be up to 50cm thick. Storm snow from the 16th was a mixture of DFs and graupel.

Rapid warming conditions were observed today with easterly aspects up to 10,000' becoming wet and saturated. Several touchy D1 loose wet results on E facing test slopes after 1230pm. Northerly aspects were also rapidly warming and the prviously dry storm snow was transitional and sticky up to about 9800'. S facing slopes were also becoming wet up to 10,200' by noon.

Lots of new reactive wind slab development above 10,000' today on W-SW-S-SE aspects thanks to continuously moderate NE winds at ridgetops. New slabs were 1F hard thanks to the high temps and were sitting atop F hard DFs and graupel above the 0416 melt-freeze crust or previous wind drifts. Several small but reactive results from kick tests and ski cutting the W aspect of Red Cone. Snowpack tests on the S aspect of the Red Cone summit ridge (10,300') showed the new slabs to have potential for both fracture initiation and propagation. CTE and CTV SP down 17cm under 1F hard wind slabs failing on a thin layer of NSF above the 0416 MFcr. ECTP4 and 6 at the same interface. New deposits on W aspects were small and stretched about 30' down the slope. On S aspects new slabs were more uniform and stretched across most of a slope and down the slope about 50'. The sun was working on the surface and the tops of the new wind slabs were transitioning to moist.

Snowpack photos: 
One of several D1 loose wet results on E aspects. Wet snow sliding on the 4/16 MFcr down up to 25cm below the surface.
One of several ECTP results on a wind loaded S aspect at 10,300'.
Small results in new wind slabs on a W aspect.
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
Clear
Air temperature: 
Above Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Northeast
Accumulation rate: 
None
More detailed information about the weather: 

Northerly winds were stronger and more consistent in duration than expected with blowing snow visible along the whole Mammoth Crest all day. Intense solar radiation under clear skies. Tsurf and T-20 were up to 0deg C on E aspects up to 10,000' by 1130am.

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