Snow conditions, Propagating Test results

SNOWPACK OBSERVATION
Sherwin ridge
Submission Info
Forecaster
Wednesday, December 30, 2020 - 1:00pm
Red Flags: 
37° 36' 33.9876" N, 118° 58' 59.286" W
Snowpit Observations
More detailed information about the snowpack: 

I toured up to the Sherwin ridge today above Mammoth rock to get a feeling for recent Wind transport and to continue to track on the Dec 12 PWL.

It was a relatively warm day today with the temperature hovering right around freezing and light to moderate winds at lower elevations. I noted remarkably little wind effect along my ascent. Most trees still held pillows of snow from the storm on Dec 28th and I observed only minor surface stiffening on some commonly cross-loaded terrain features. Upon reaching the ridge I noted only the most exposed areas along the Northerly facing terrain had been stripped during the recent north winds. this may be short lived though, I noted the winds had shifted and were blowing out of the west at around noon today. Intermittent moderate winds were beginning to blow snow around, and I observed plenty of low-density snow on the back side of the ridge. If these winds continue as they are forecasted to do, I suspect some decent loading on more northerly and easterly terrain in this area.

I dug in at around 9300’ on a 25° slope NE aspect near a feature called the Hose. HS=72 cm

I found the same poor structure I have been finding throughout the forecast area and had very similar test results. A compression test showed Sudden Collapse Fracture character under moderate load (CT12 SC) and I saw propagating results on both my ECT tests as well as my Propagation Saw test. (ECTP-21 X2, PST35/100 END) All this points to the energy in this particular weak layer at this location and the potential for a failure to propagate across a slope. A big caveat here is that there simply isn’t a ton of snow and the areas with the right set up, presence of old faceted basal snow, AND a stiff enough slab seems to be isolated across the landscape. Periotic probing shows the extreme variability in the distribution of both of these factors. I suspect we will need a significant load to see substantial activity on this PWL. No other signs of instability were observed on my tour today.

 The recent Low-density snow has improved the surface conditions quite a bit since my last visit to the area, but shallowly buried rocks, logs, bushes, and trees still litter the landscape. Despite my best effort to move slowly and avoid the rocks I still managed to leave behind quite a bit of ptex on my descent back to the car.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Cooling
Wind Direction: 
West
Accumulation rate: 
None
More detailed information about the weather: 
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