Natural on Becker Peak

Location Name: 
Becker Peak
Region: 
Echo Summit Area
Date and time of avalanche (best estimate if unknown): 
Wed, 03/31/2010 - 04:00
Location Map: 
United States
38° 49' 56.406" N, 120° 3' 32.4144" 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: Professional Observer
Avalanche Observations
Avalanche Type: 
dry,slab,loose,
Slope: 
40degrees
Trigger type: 
Natural
Crown Height: 
Less than 1 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
200ft.
Terrain: 
Near Treeline
Elevation: 
8 200ft.
Bed Surface: 
Storm Snow
Avalanche Length: 
700ft.
Number of similar avalanches: 
5-10
More detailed information about the avalanche: 

Several small soft slab and loose snow avalanches were observed on surrounding peaks on E and NE facing slopes. All appeared to have fractured on a density change in precip particles (stellars still visible) 10cm to 15cm below the surface. Although the pictured debris (picture 2) appears wide enough to be one slab avalanche, it is actually several small slab and loose snow avalanches in close proximity. None of the observed avalanches were bigger than a D1.

Picture 1: Start zone in E,SE facing rocks

Picture 2: Path and deposition zone, E facing

Picture 3: None of the observed avalanches stepped-down to this graupel layer on top of pencil hard melt freeze crust. Slab density in this area was still very light (skiing incredibly well). Compression Tests and Extended Column Tests showed progressive compression in the low density PPs above the graupel layer, effectively absorbing any force that might have impacted the graupel layer. If slab density increases, or where it already has, this graupel layer may become a concern.

Picture 4: Test slopes showed consistent soft slab/loose snow fractures on the same density change within the new snow PPs from 10cm to 15cm below the surface. Minimal propagation from ski cuts.

Hst = 40 to 60cm

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Yes
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
West
Accumulation rate: 
None
More detailed information about the weather: 

S1 precip tapered off around 11:30AM to 25% cloud cover. Winds were light until mid afternoon when they increased to moderate.