Wind Slabs on Chicken Wing

SNOWPACK OBSERVATION
Submission Info
Forecaster
Thursday, April 13, 2017 - 2:00pm
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
37° 45' 24.9912" N, 119° 2' 10.0896" W
Snowpit Observations
More detailed information about the snowpack: 

Toured up NE aspect of Chicken Wing, tested cornices and small wind loaded slopes at the top, skied down low angle trees back to the car.

Very windy today: moderate to strong S winds at the trailhead. Widespread moderate blowing snow. 5cm of moist new snow up to about 8500'. Above about 8500', new snow was 10cm deep and dry. Thin, 2cm, melt-freeze crust from early in the week was moist and breakable under the new snow below 8500', firm and hard above that elevation. Under that crust the storm snow from last weekend was 50cm deep and moist all the way down. Under that was the melt-freeze crust that was buried on 4/6. It was wetted through.

Winds were tamer in the sheltered trees. But above about 9200' they were again moderate to strong and variable in direction. Widespread moderate blowing snow (see videos). Now cracking until the top exposed ridge. Stomped on cornices and test slopes at the summit ridge where the wind was strongest from the SW. E facing cornices had limited, localized cracking (see photo). But, slope testing the wind loaded NNE ridge below the summit was more reactive. Triggered a 50' x 50', 30cm thick slab at 9600' on a 32 degree slope. Slab did not slide and over run the stauchwall. Probably because the slope was not quite steep enough. (See photos)

Ski cutting and cornice testing are advanced skills that require experience to be done safely. Skier safety in number one when testing slopes. These results were expected and the slopes were chosen carefully for the low consequences of triggering a slab.

Snowpack photos: 
Test slope results.
Test slope results: 50x50 slab.
Intentionally triggered wind slab.
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

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