Donner Peak Snowpack Observations

Location Name: 
Donner Peak
Region: 
Donner Summit Area
Date and time of observation: 
Sun, 01/17/2016 - 12:00
Location Map: 
United States
39° 18' 42.372" N, 120° 19' 0.768" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Obvious avalanche path
Terrain Trap
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Revisited Donner Peak today to compare results from yesterdays observations that were showing sudden collapse fractures on buried surface hoar.  In similar locations to yesterday, we were able to identify the layers of concern down 75-80cms.  Consistent sudden planar fractures were shown with CT's in the easy to moderate range but ECT's had mixed results with some that would propagate and some that did not.  Yesterday, skier collapses occurred in this area and today no other signs of instabilities were observed. A 10cm wet surface rain crust has developed in this area up to at least 7500'.

Crown line profiles were conducted in the below mentioned avalanches.  None of these snowpack tests indicated that the instability that caused these avalanches was still present or active.

Photo #1-3:  An avalanche thought to have occurred sometime late Thursday/Friday.  N-NE aspect, 7400-7500',  in a small gully feature.  400-500' wide and ran downslope 30-250'.  Thought to have failed on the buried surface hoar layer.

Photo #4:  An avalanche just below the Poop Chute near the parking area.  Crown measured 3' deep and ran below the main cliff bands and around rock features.  NW-N aspects 7200'.  Thought to have failed on the buried surface hoar layer.

Snowpack photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Strong
Precipitation: 
Mixed rain and snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Winds and snow picked up in the early afternoon.  Snow level was around 7000'.