Skier triggered avalanche lower Negatives

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AVALANCHE OBSERVATION
Slope btw. Hourglass and Negatives bowl
Submission Info
Wednesday, February 15, 2017 - 10:15am
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Avalanche Type: 
Dry
Slab
Slope: 
35degrees
Trigger type: 
Skier
Aspect: 
Northeast
Weak Layer: 
Old Snow
Avalanche Width: 
30ft.
Terrain: 
Near Treeline
Elevation: 
9 800ft.
Bed Surface: 
Old Snow
Avalanche Length: 
60ft.
Number of similar avalanches: 
1
More detailed information about the avalanche: 

 

 

 

 

 

Weds 2/15. Windier than expected, very fresh and very reactive new windslabs at the mid-elevation NE aspect I visited.

rode the June lifts to the top and traversed over toward the Negatives. After 2-3 days of nice weather and light winds, figured it could go. Forecast was for another day of light wind and steady temps. Heading over, noticed lots of snow transport happening on the ridges, particularly in the hourglass, which looked fat with new wind slab (see photo)

Decided to instead climb the sparsely treed slope to lookers right of the Hourglass, which appeared less steep, had no visible snow transport going on, and had multiple ski tracks from prior days that had not been covered. Most of the climb was soft snow with 10-15cm ski penetration. At approx 9800' started encountering patches of harder, hollow-feeling snow. A few steps later, cracks shot 3m ahead of me and a very small slab approx 3m x 3m x 10cm deep broke and slid a few feet (see photo).

Turned around there and traversed back a bit to where the snow seemed softer and more stable. Third turn down, a very soft slab approx 10m across and 25cm deep broke below me. Was able to ski away from it easily and watch it run approx 30m. Did not hang around to take pictures. Slab was deposited overnight or that morning and was surprisingly reactive, noticed lots of shooting cracks later on safer terrain. Weak layer was the interface with the firmer snow surface from yesterday and was surprisingly poor bond.

 

 

 

 

 

Avalanche Photos: 
Blowing Snow: 
Yes
Cloud Cover: 
Clear
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
None
Number of People Caught: 
1
37° 43' 42.258" N, 119° 5' 27.0708" W

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