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Skier Triggered Avalanche in Sun Bowl

Submitted by akiefer on Sat, 12/17/2016 - 8:25pm
Location Name: 
Green Butte, Sun Bowl
Region: 
Mt. Shasta
Location Map: 
United States
41° 22' 12.7452" N, 122° 12' 54.324" W
US
Observation made by: 
Forecaster
Date and time of avalanche (best estimate if unknown): 
Sat, 12/17/2016 - 4:00pm
Red Flags: 
Recent avalanche activityRecent loading by new snow, wind, or rainObvious avalanche path
Avalanche Observations
Avalanche Type: 
DrySlab
Slope: 
35degrees
Trigger type: 
Skier
Crown Height: 
1 ft
Aspect: 
South
Weak Layer: 
Other - explain below
Avalanche Width: 
600ft.
Terrain: 
Above Treeline
Elevation: 
8 700ft.
Bed Surface: 
Old Snow
Avalanche Length: 
800ft.
Number of similar avalanches: 
1
Number of people caught: 
2
More detailed information about the avalanche: 

Avalanche Classification Code: SS-AS-u-R3-D2

Preliminary Information:

Two backcountry skiers were caught, carried, remained on top of the snow surface, and were uninjured in this avalanche.  The avalanche occurred on a south aspect at 8700ft in Sun Bowl off of Green Butte Ridge. The estimated dimensions of the avalanche are as follows: crown depth 12-18", 600ft wide, 800ft vertical run.  The avalanche failed within newly wind deposited snow that likely formed yesterday and today.  The avalanche occurred while both skiers where descending the slope.  One skier had fallen and lost a ski, and as the second skier traversed across the slope to help retrieve the ski, the avalanche was triggered.  Both skiers were able to ride the flowing avalanche debris to a stop at the bottom of the slope without being injured or buried.

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
Clear
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
West
More detailed information about the weather: 

Continuous wind transport of snow was observed throughout the day.  Average wind speeds were moderate with strong gusts.  Wind direction was variable and was observed blowing from the SW, W, and NW.  Temperatures ranged from 15-20F and skies were sunny and clear.