Small slab avalanche in Nat Geo Bowl

Location Name: 
National Geographic Bowl, Granite Chief
Region: 
Cabin Creek, Deep Creek, or Pole Creek Area
Date and time of avalanche (best estimate if unknown): 
Sat, 02/25/2017 - 12:30
Location Map: 
United States
39° 11' 55.8132" N, 120° 17' 17.4084" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Observation made by: Guide at Alpenglow Expeditions
Avalanche Observations
Avalanche Type: 
Dry
Slab
Slope: 
40degrees
Trigger type: 
Skier
Crown Height: 
Less than 1 ft
Aspect: 
Northwest
Weak Layer: 
Storm Snow
Avalanche Width: 
30ft.
Terrain: 
Above Treeline
Elevation: 
8 800ft.
Bed Surface: 
Old Snow
Avalanche Length: 
250ft.
Number of similar avalanches: 
1
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
More detailed information about the avalanche: 

We have been seeing increasing stability in this zone the last several days, and have been slowly pushing into more aggressive terrain.  The main problem we have been dealing with is loose dry sluffs and today we triggered two small windslabs in steep, near ridgeline terrain. Both slides were easily managed by the skiers, and did not grow big enough to bury or injure a skier. Crown height was between 3-6". Numerous other ski cuts and additional tests did not show any other signs of slab instabilities today. 

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Accumulation rate: 
None
More detailed information about the weather: 

Cold temps and moderate solar radiation today.