Donner Summit/Sierra Crest Observations

Location Name: 
Donner Summit
Region: 
Donner Summit Area
Date and time of observation: 
Fri, 02/12/2010 - 11:00
Location Map: 
United States
39° 17' 13.4916" N, 120° 19' 22.9368" W
See map: Google Maps
US


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

Rain crust up to 8200' in this area with a trace to 2'' of heavy high density snow on top.  In the highest wind loaded terrain at or above treeline N-E aspects had up to 4-6'' of 1F hard snow.  These wind loaded areas were very localized and were not reactive to ski cuts/ski kicks.  The rain crust had variable ski support on all aspects and elevations.  SW winds were moderate to strong in speed for all of the day, snow transport decreased into the afternoon as the available snow was scoured down to the rain crust.  Hand pits in the upper wind loaded terrain did reveal shear failure directly above the rain crust.  Had consistent moderate CT's on this layer but no propagation with the ECT.  Did have some very localized shooting cracks in wind loaded terrain.  Had some roller ball activity off ski tips while skiing at lower elevations on solar aspects.  Overall stability was good except for some concern with the small wind slabs at or above treeline on N-E aspects.        

Photo #1: Debris pile off of the Sierra Crest/Anderson Ridge.  Looked to be from a cornice failure, N aspect, 8000'.  Visibility was poor with flat light but it appeared to be recent.

Photo#2:  North facing ridge off of Mt. Lincoln/Sierra Crest with some cornice drop on slope. 

Snowpack photos: 
Any other comments about the observation or links to outside pages that have more info on the observation: 

 

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Strong
Precipitation: 
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: