Small wind slabs, shooting cracks, and loose snow sluffs on Silver Peak

Location Name: 
Silver Peak
Region: 
Cabin Creek, Deep Creek, or Pole Creek Area
Date and time of observation: 
Wed, 02/20/2013 - 12:30
Location Map: 
United States
39° 13' 24.0312" N, 120° 14' 37.3452" W
See map: Google Maps
US


Red Flags: 
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: 

Below 7000 ft about 2 inches of new snow had accumulated. At elevations above 7000 ft and closer to the Sierra Crest 4-8 inches of new snow existed. Snowpit data revealed that a density change still exists within the new snow and that the new snow rests on top of a rain crust with weak sugary snow below it. Tests on both of these weak layers did not indicate significant instability in non wind loaded areas. In some sheltered areas some skier triggered sluffs did occur on steep test slopes.

On the more exposed near and above treeline slopes, last night's strong NE winds had scoured significant amounts of snow away from the N-NE-E aspects and deposited new wind slabs onto the SE-SW-W aspects. Some of the N-NE aspects also still had wind slabs remaining on them in near and above treeline areas on Silver Peak. In these more wind loaded areas tests resulted in unstable results due to wind slab failure.Some skier triggered shooting cracks did occur in areas where these wind slabs existed. In this area most of the wind slabs remained relatively small and quickly dissipated as one moved away from the ridgelines. The deepest wind slabs measured 10-12 inches in this area.

Photo 1: A near treeline aspect scoured by the NE wind

Photo 2: Skier triggered shooting crack in a wind slab on a SE aspect.

Photo 3: A skier triggered loose dry sluff on a 39 degree N facing below treeline test slope.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Accumulation rate: 
More detailed information about the weather: 

The winds had died down by 10am in this area. Ridgetops exhibited calm conditions. The clouds above the mountains were moving towards the SW indicating NE winds above the mountain tops.