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Professional Observation

       

Basic Information

Observation Details

Observation Date:
December 28, 2022
Submitted:
December 28, 2022
Observer:
Everett Phillips | ESAC Forecaster
Zone or Region:
Mammoth Lakes
Location:
Lakes Basin - wind slab avalanche activity

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced

Key Points

Post storm lap in the Mammoth Lakes Basin today to verify the forecast (problems and danger levels). Here are my takeaways:

  • The wording of the bottom line and the wind slab problem from this morning’s forecast rang true for me today. While wind loading was not as intense or widespread as expected in the Lakes Basin today, large wind slab avalanches were easy to trigger near and above treeline in specific areas.
  • Wind slabs can be tricky to work around. They can be deceptively deep and the hardness of the slab can propagate failure through the snowpack across large terrain features. Use care when testing for wind slab instability. Today I ended up triggering the problem I wanted to investigate from a safe distance, but it still felt too close for comfort.
  • No avalanche activity was observed within the old snow post-storm, despite a good view of many start zones where the persistent slab problem is forecasted. This storm was a good test for the old layers. In the lakes basin they passed the test.

Overall a beautiful day to be out in the mountains!

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Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
19F @ 10,400'
Wind:
Light , SW

Clear skies, light winds decreasing through the day.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Today Redcone Bowl
N 10400' 		D2 SS S-New Snow AS-Skier
r-Remote 		Triggered by forecaster while kicking cornices on the ridge above the start zone. None
2 Past 24 hours Jaws - Lakes Basin
NE 10700' 		D1.5 SS S-New Snow 2 N-Natural None
1 Past 24 hours Redcone Bowl (Low on skiers right)
W 10000' 		D1.5 HS S-New Snow 2 ft. U-Unknown None

Snowpack Observations

Ski pen was around 35cm all day today, make of that what you will. Height of snow in the Mammoth Lakes basin is now over two meters. That is my usual benchmark for a deep snowpack, and as they say “a deep snowpack is a strong snowpack”. Below treeline and above treeline I was able to probe for the 12/01 facet layer and got it consistently at around 170cm below the surface. A quick test pit at 10400′ on an E aspect revealed no specific layer of concern within the upper meter of the snowpack.

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