Wind loading and a stout rain crust in the Sherwins

Mammoth Rock
Submission Info
Saturday, December 14, 2019 - 12:30pm
Red Flags: 
Recent loading by new snow, wind, or rain
37° 36' 37.0188" N, 118° 59' 28.95" W
Snowpit Observations
More detailed information about the snowpack: 

I went for a mid-day tour in the Sherwins to get an idea of how the new snow and strong winds have been affecting the surface conditions.  I left the car at about 1030 this morning, the temperature was in the mid ’20s, and the wind was blowing, making for a brisk skin up to the ridge above Mammoth rock.  The strong winds have had quite an impact on the area, and surface conditions are quite variable. While I did observe new snow totals around  3-5” in well-protected areas, I did not see any storm slab instabilities today. It was hard to find places representative of the recent snowfall that had not been affected by the wind. Most notably, I found many exposed areas that have been stripped to the recent rain crust witch I observed up to ~ 10,000’~. It seems to be well bonded to the snow below, and for the most part, it was supportable.  

 I was able to find fresh wind slabs ranging from 2-7” thick. Some in places you would expect like the exposed ridgeline and some cross-loaded features along the ascent where active wind loading was observed. I also found thin wind slabs in more well-protected trees mid slope. For the most part, these isolated pockets of wind slabs were very thin and not very consequential. But it was impressive to see all the nooks and crannies that have been affected by the recent gale-force winds. 

 The most significant hazard today seemed to be the variable surface conditions. Particularly, the combination of the exposed rain crust and preseason obstacles like fallen trees, and rocks.  More than once I found myself picking up more speed than I had bargained for on the ice. Deliberate and controlled skiing is certainly advised.

Snowpack photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Air temperature trend: 
Wind Direction: 
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

I left the car with partly cloudy skies this morning. The temperature was in the mid 20°sF and the wind was strong out of the SW.  At around 1130 the clouds moved in and visibility rapidly decreased as snow began to fall.  The temperatures stayed relatively cold throughout my tour and the strong winds continued out of the SW. 


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