D2-R4 Wind slab in National Geographic Bowl

Location Name: 
Needle Peak
Region: 
Cabin Creek, Deep Creek, or Pole Creek Area
Date and time of avalanche (best estimate if unknown): 
Thu, 03/17/2011 - 15:53
Location Map: 
United States
39° 12' 11.0592" N, 120° 17' 38.4468" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Public
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
38degrees
Trigger type: 
Natural
Crown Height: 
2 ft
Aspect: 
Northeast
Weak Layer: 
Storm Snow
Avalanche Width: 
900ft.
Terrain: 
Above Treeline
Bed Surface: 
Old Snow
Avalanche Length: 
1 000ft.
Number of similar avalanches: 
5-10
More detailed information about the avalanche: 

This photo was taken from near the top of Granite Cheif looking west towards Needle & Lyon peaks. A large wind slab broke free in the last 24 hrs. on the NE shoulder of Needle Pk. and ran the distance. The crown height was about 2+ feet on lookers right tapering to less that 1 foot on the left. Several isolated step-downs (6"-12") within the slide path were observed. Aproximate width of the crown was 900'. The bed surface was about 500' long (tall), the total runnout was about 1000'.

The black line drawn in the photo traces the crown (my cell phone camera does not show much detail).

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
Clear
Air temperature: 
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: