Strong NE Winds and Small Windslabs on Andesite Peak

Location Name: 
Andesite Peak
Region: 
Donner Summit Area
Date and time of observation: 
Wed, 02/20/2013 - 09:00
Location Map: 
United States
39° 21' 2.0808" N, 120° 21' 59.4108" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

6-8'' of new snow in the Castle Peak/Andesite Peak area in protected locations.  As the storm was winding down Wednesday evening the winds switch over to the NE and increased in speed overnight as per the remote weather data.  NE winds were strong and consistent all morning moving snow.  All exposed N-E aspects at treeline and above were wind scoured back down to the old snow surface rain crust.  This snow was being moved onto S-W aspects and creating small but reactive windslabs.

The available snow for transport was declining by mid morning as most all exposed terrain was scoured back down to firm rain crusts.  Newly formed windslabs on S-W aspects  were reactive to ECT's (see videos) and also to the weight of a skier with shooting cracks and small windslab failure.  No evidence of any avalanche activity occuring during the storm while SW winds were loading NW-E aspects, although all those areas were severely scoured. 

Photo#1:  8000' Andesite Ridge, NE-E aspect scoured down to old snow surface rain crust by the strong NE winds.

Photo#2:  7600', Andesite Ridge, S aspect, small windslab failure

Photo#3:  Wind effect in protected trees at 7300', north aspect.

Video #1:  ECTP-3 on 6'' windslab.  8000', W aspect, 30 degree slope

Video #2:  Strong NE winds at 8000' on Andesite  Ridge

Video#3:  ECTP-6 on 4-6'' windslab.  8200', W aspect, 30 degree slope.

Snowpack photos: 
Snowpit videos (tests, etc): 

AndesitePeak2013 2 20 008

AndesitePeak2013 2 20 011

AndesitePeak2013 2 20 012

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