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Above treeline observation on Mt Shasta

Location Name: 
Green Butte/Old Ski Bowl
Region: 
Mt. Shasta
Date and time of observation: 
Thu, 01/12/2017 - 10:30pm
Observation made by: 
Forecaster
Red Flags:

Location Map

United States
41° 22' 18.5772" N, 122° 12' 21.456" W
US

Snowpack Observations

Details

Total height of snow unknown, could not hit ground. Overall, soft and smooth snow surface conditions above treeline. Isolated sastrugi and erosional features in windy locations, ridgelines, etc. I did not view any super recent avalanches, although at some point during this past week, the entire east aspect of Green Butte came down, likely a soft wind slab or storm slab combo. Debris was piled up and visible from about 9,000 feet down to 8,400 feet, approx. Skiing and riding conditions were superb. A few bold folks center punched Sun Bowl. The snowmobilers were a safer bunch today and kept riding on lower angle slopes. The main goal today was to take a look at above treeline terrain and assess wind slab formation, distribution and sensitivty. Overall, moderate avalanche danger was observed. At my snow profile location, about a 35cm hard wind slab sat on top of lighter density snow. It was at this density change where all failures within tests took place.Moderate to hard failures produced clean shears at this layer within small and large column stability tests, however full propagation on a slope scale I feel would be tough, though not impossible. Multiple riders on a slope or near the edge of a wind slab could potentially trigger a hard wind slab. 

Snow Pit Photos

Photos

  • East aspect of Green Butte, this entire slope slid sometime in the past week.
  • Same easterly aspect of Green Butte that avalanched during this past week
  • Looking up into the Old Ski Bowl from about 9,000 feet
  • Snow surface conditions above treeline on Mt Shasta

Weather Observations

Details

East/Northeast winds, light to moderate, blowing snow onto leeward westerly slopes. Cold temps and icy snow grains preventing good wind loading characteristics. 

Statistics

Cloud Cover: 
Clear
Blowing Snow: 
Yes
Precipitation: 
None
Accumulation rate: 
None
Air temperature: 
Below Freezing
Air temperature trend: 
Static
Wind Speed: 
Moderate
Wind Direction: 
Northeast