Rain and Facets on Mt. Judah

Location Name: 
Mt. Judah
Region: 
Donner Summit Area
Date and time of observation: 
Wed, 12/09/2015 - 12:00
Location Map: 
United States
39° 18' 22.6692" N, 120° 19' 2.6976" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Basal facets existed in areas at 7700-7900' on North aspects in the Mt. Judah area.  These facets were moist and very cohesive but were much larger grain size and less dense than the layers above. Most of the tests targeting this facet layer at 2 locations showed unstable results.  Extended column tests indicated that fractures can travel through these layers and these fractures also propagated in longer 2m  ECT's. In many areas these facets are on the ground and are held in place by terrain and anchors(trees, rocks, bushes, logs, etc.)  In areas that have relatively smooth ground cover fractures in this layer could travel for longer distances. 

Snowpit results and locations:

Wildflower Ridge, N 39.30708, W 120.31809, 7775', 32 N, 30 slope angle, HS 62cm =ECTP17 @0cm.  2mECTN20 @0cm.  ECTP25 @105cm

Mt. Judah, N 39.30657 W 120.31728, 7875', 10 N, 33 slope angle, ECTP11 Q1 @0cm, (2x) 2mECTP11 @0cm.  

Photo: Snowpack structure showing the crust facet layering. 

Video: 2m ECTP at the Mt. Judah location.

Snowpack photos: 
Snowpit videos (tests, etc): 

Fracture Propagation through Facets on Mt. Judah in a 2m Extended Column Test

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

Rain started falling at 11am on Donner Summit. Rain continued through the afternoon.