Thin snow coverage, poor Structure and propagating test results in the Lakes basin

Lakes Basin
Submission Info
Friday, December 18, 2020 - 12:30pm
Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
37° 35' 42.09" N, 119° 1' 28.8372" W
Snowpit Observations
More detailed information about the snowpack: 

I traveled to the Mammoth Crest today via the Red Cone ridge to get a look at Multiple aspects and elevations in the Lakes basin.

My takeaway from today is that the coverage is quite variable with Snow heights ranging from 35 cm to almost a 1 meter depending on your aspect and elevation. The Mammoth area seems to have the most reliable coverage in the forecast area though many hazards still abound in the form of shallowly buried rocks, fallen trees, and exposed bushes.  Westerly and southerly aspects are much thinner and the snow coverage (if present at all) is largely new snow from the more recent December storms.  Looking around at the more alpine terrain coverage seems pretty thin. Strong winds seem to have limited the deposition of our past few storms in the alpine to gully features and catchment zones.

I dug three pits today on multiple aspects and elevations. (see profiles below) I confirmed poor structure on Northerly and Easterly aspects with the December snow resting on the older weak November snow. This older snow now makes up a variety of facet crust combos residing underneath a consolidating slab. My tests produced propagating test results in both areas that presented the poor structure and these failures exhibited sudden collapse fracture character.  In addition, I encountered a couple areas near and below tree line where I experienced isolated collapsing. I also found a few terrain features where I was able to initiate isolated surface cracks and even a very small size one avalanche on these lower facet layers. On the approach I encountered a small avalanche which had run across the skin track. (see photos below) This slide occurred on a small terrain feature and was remotely triggered from about 3 meters away.  Further evidence that the conditions exist in the snowpack to produce more sizable avalanches in the right location.

Moderate NE winds were certainly doing their best to move snow near and above tree line today. I noted Flagging along the Crest this morning and found many areas on southerly and westerly aspects where my body weight was enough to break loose small wind pockets (4-6” deep.)

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Cloud Cover: 
Air temperature: 
Below Freezing
Wind Speed: 
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

Sunny skies and cool temps made for plesent day today. Moderate to strong NE winds were moveing snow around near and above tree line 

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