Loose dry activity on Andesite Ridge.

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of observation: 
Thu, 04/14/2016 - 10:45
Location Map: 
United States
39° 21' 3.7188" N, 120° 21' 58.2804" W
See map: Google Maps
US



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

Signs of instability were limited to loose dry avalanches in this area this morning. New snow amounts of 10 cm were present. Wind loading was isolated at 30 to 45 cm deep but did not extent more than 1 m down slope. Bonding of new snow to the old snow melt-freeze crust surface was fairly poor, but some cohesion was observed.

Photo 1: Snowpack structure of 10 cm new snow on top of 10 cm thick P hard melt-freeze crust over deep wet snow.

Photo 2: Cohesive, moist snow but still acting like loose dry avalanches on test slopes in response to ski cuts.

Photo 3: Wind pillow on ridgetop, wind loaded 30 to 45 cm, but only extending 0.5 to 1 m down slope. Ski cuts still produced loose dry rather than slab activity in this area (Noted lat/long). ECTN results in wind pillow on adjacent slope.

Photo 4: Loose dry activity in response to ski cut. Slope angle steeper than 40 degrees was generally required for test slope failure to occur.

Photo 5: Sun breaks on the Sierra Crest were very infrequent and always lasted less than 3 minutes this morning in the Donner Summit area. Despite the isolated periods of sun, a thin sun crust formed quickly in open areas on E-SE aspects.

Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Off and on periods of snow showers.