Reactive buried surface hoar, Negro Canyon

Location Name: 
Top of Negro Canyon
Region: 
Donner Summit Area
Date and time of observation: 
Sun, 01/10/2016 - 13:10
Location Map: 
United States
39° 20' 47.8968" N, 120° 18' 21.834" W
See map: Google Maps
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Observation made by: Guide at Alpenglow Expeditions
Snowpit Observations
More detailed information about the snowpack: 

At the top of Negro Canyon (7,500', N aspect), once again we found both the Jan 5th and Jan 9th buried SH. Unlike yesterday's obs, the jan 5th layer was reactive today. Several ECT's in this location produced a clean, planar failure across this layer. (see video)( ECTP11 x1, ECTP12 x2). Informal ski test above the skin track on steep rollovers (40+) produced 2-3' shooting cracks, failing on this layer. 

The Jan 9th layer was very present on Northerly aspects today as well, and is buried approx 4-5cm down in this location. Surface hoar was quite large at this location, with the largest @ 12+mm. (see photo). The SH has "layed down" somewhat, but was very sensitive to informal tests and shovel shears. 

Snowpack photos: 
Snowpit videos (tests, etc): 

ECT 20160110

Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Cooling
Wind Direction: 
Accumulation rate: 
None
More detailed information about the weather: 

Nice day, moderate solar radiation and below freezing air temps. Very little wind.