Small Wind Slabs on Mt. Judah

Location Name: 
Mt. Judah
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Sat, 12/15/2012 - 11:00
Location Map: 
United States
39° 18' 15.1848" N, 120° 19' 3.378" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
dry,slab,
More detailed information about the avalanche: 

Wind slabs were forming today on N-E aspects in wind prone areas.  These wind slabs were very easy to trigger with a small ski kick in the morning hours and were all failing on the density change from the newly formed wind slabs and the old low density snow.  In the more exposed areas these wind slabs got up to 40cm deep by late morning.  All of these avalanches were small, D1, and posed little risk to backcountry users at the time of my observations.  SW winds increased from moderate in the morning hours to strong in the mid day hours moving much more snow with plenty of low density snow for transport.  These windslabs are expected to increase greatly in size as the day continues and pose more risk to backcountry users.

Photo #1 and #2:  Small windslabs intentionally triggered off of Wildflower Ridge.  7800', north aspect, 35-40 degree slope.  20-25cm deep.

Photo #3 and #4:  Small windslabs intentionally triggered off of the East Face of Mt. Judah, 8200', East aspect, 35 degrees.  30-40cm deep.

Video:  PST 60/100 END on the 12/2 facet layer.  7800' on a 35 degree slope, north aspect on Wildflower Ridge.  HS=260cm

Snow coverage is thin below 7500'.

Avalanche Photos: 
Avalanche observation video: 

DonnerSummit2012 12 15 005

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: