Unstable wind slabs on Carpenter Ridge

Location Name: 
Carpenter Ridge
Region: 
Independence Lake Area
Date and time of observation: 
Thu, 02/24/2011 - 10:00
Location Map: 
United States
39° 24' 45.6804" N, 120° 18' 55.4364" 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
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Photo 1: Avalanche 1 to 3 days old that was likely triggered by cornice collapse either human intentional or natural.

Photo 2: Skier triggered cracking on approach of the west end flank of the avalanche in photo 1.

Photo 3: Test slope failure/very small avalanche of wind slab just off east end of flank of avalanche in photo 1. Remotely skier triggered from 5 feet away while on the ridgetop.

Photo 4: Crown of test slope failure in photo 3.

Elevation stated in the video segment is incorrect. Correct elevation is 8,600' not 8,900'.

Very significant amounts of blowing snow in this area. New snow accumulation of 2 inches at 10am was well on track to exceed forecast amounts of 2 to 3 inches total accumulation prior to 4pm. Ongoing wind loading from a mix of new snow and transport of old snow on the ground was adding to already unstable wind slabs in this area. Wind slabs continuing to fail on an upside down layer that formed at the tail end of the last storm cycle. Slabs in this area are composed of 1F hard snow at their base on top of 4F hard snow as a bed surface.

Snowpack photos: 
Snowpit videos (tests, etc): 

20110224 Carpenter Ridge.MOV

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: 

Gale force winds on the ridgetops at 8,600' elevation.