Isolated sensitive winds slabs at Carson Pass

Location Name: 
Elephant's Back
Region: 
Carson Pass Area
Date and time of observation: 
Wed, 04/11/2012 - 14:00
Location Map: 
United States
38° 40' 46.2468" N, 119° 58' 58.9332" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap
Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Pic: 10cm of very low density new snow was available for wind transport, with sensitive wind slabs forming just beneath ridgelines.

Video: A little hard to see, but column did not fail on the planar surface visible at end of test. Column failed and propogated on low density stellars just above crust, that are blocked from view in video by remaining column that fell off but did not move out of the camera frame. The planar surface visible at end of test was a secondary failure layer. Also 2x ECTPV with same failure layers. 2 small natural slab avalanches had occured adjacent to my tests, but had been covered by enough additional wind loading that I couldn't discern failure layers. Possible small natural cornice fall a triggers. Ski cuts did produce shooting cracks, but no slope failure.

This sensitive wind slab existed just below ridgelines, but quickly changed to 20cm of non-reactive, low density snow on top of supportable crust away from ridgelines, and 10cm on wind sheltered slopes.

 

Snowpack photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
West
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: