Variable surface conditions and propagating test results in the sherwins

SNOWPACK OBSERVATION
Mammoth Rock
Submission Info
Forecaster
Friday, December 20, 2019 - 12:00pm
Red Flags: 
Recent loading by new snow, wind, or rain
Snowpit Observations
More detailed information about the snowpack: 

I went for a tour in the Sherwins today to get a look at the rain crust below tree line and get a feeling on the extent of the faceting that has been observed near this crust. Leaving the car at 9 am, the temperature was 34°F, skies were overcast, and light winds were blowing from the southwest. Surface conditions are quite variable, and I found the crust up to the ridge above Mammoth rock.  In the sheltered trees above 9000’ or so, the conditions were enjoyable, 15-20 cm of recycled powder. Below 9000’ the surface conditions were much more variable, and the rain crust was more prevalent, ranging from breakable and grabby to supportable and slick. Some minor blowing snow was visible at lower elevations and cross-loaded features, but no major flagging on ridge tops.  I also observed some small, shallow cracks on my ascent and found some fresh wind deposits between 5-20 cm thick. For the most part, these fresh drifts were loose and relatively unconsolidated. I did not find any observed recent wind deposits to be concerning. If anything, it was beneficial for the ski quality.

 

I dug two snow pits today the first at 9300’ in protected trees. And the second on a 40° wind loaded slope near the top of the hose on the ridge.

1)HS=97cm. Mostly right-side up with 2 distinct crust layers. Observations from this pit suggest that the rain crust is continuing to break down, but I still found it to be 2 cm thick and Knife hard at this location. Immediately below this layer, I found loose faceted grains. The rain crust is only 15cm below the surface and was reactive to my tests today. (CT11 SC @ 82cm, ECTP 12 @82cm)

2)HS=295CM. I dug down ~1.5~ meters and found a right side up dense snowpack. I identified the MF layer about 50cm below the surface. At this elevation, the crust is much less of a lens. I did observe 20 cm of fist hard new wind deposit on the surface immediately above 25 cm of 1F wind packed rounds. Below this layer, I identified a thin layer of facets on top of the 2cm MF crust. Below this crust, the well-consolidated pack transitioned from Pencil to knife hard wind packed rounds to the base of my hole.  While test results here were more stubborn, they did highlight the facet crust combo as a layer of concern, and both my CT and ECT tests exhibited sudden planer results. (CT23 SP down 45cm, ECTP 28 down 45cm)

 

Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
None
More detailed information about the weather: 

overcast skies broke midmorning and became mostly cloudy. temperatures remained above freezing for the entirety of my tour reaching 34* F on the ridge at 1200.  winds were mostly light this morning in the sheltered north-facing trees. on the ridge moderate winds were blowing with the occasional strong gust.

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