Vaiable conditions on Andesite

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of observation: 
Sat, 02/18/2012 - 16:00
Location Map: 
United States
39° 21' 4.644" N, 120° 22' 0.2136" W
See map: Google Maps
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Variable snow conditions existed in the Andesite Ridge area today. On the E-SE-S-SW-W aspects a firm frozen snow surface existed in most places. On some of the more shaded easterly aspects this frozen crust was sometimes breakable and sometimes supportable. On the NE-N-NW aspects conditions ranges from soft snow in sheltered areas near and below treeline to areas where all of the recent snow was scoured away by the east winds that followed the storm on the exposed NE-N aspects above treeline. 

Photo 1: Features created by wind scouring

Photo 2: NE aspect scoured back to the Jan 26th crust.

Below these surface the weak crust/facet combination still exists on the NE-N-NW aspects at the base of the new snow. Some whumphing occurred today on a near treeline NW aspect and on a near treeline NE aspect at around 8000ft. In both of these areas, ski cuts on nearby test slopes did not cause any failure. Extended column tests (ECTN14, ECTN15 on NE aspects - ECTN16,  ECTN20 on NW aspects - all of them failed in the facet layer below the Jan 26 crust). in places similar to the those where the whumphing occurred indicated that while it was not hard to initiate a fracture, it was difficult for that fracture to travel through the weak layer. These conflicting pieces of data indicate variability in the snowpack.

Snowpack photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Air temperature trend: 
Cooling
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: