Donner Summit Observationns

Location Name: 
Donner Summit
Region: 
Donner Summit Area
Date and time of observation: 
Sat, 03/31/2012 - 12:00
Location Map: 
United States
39° 18' 16.7364" N, 120° 19' 3.6876" W
See map: Google Maps
US


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

Wet snowpack in the early morning hours.  Punchy conditions below 7500' under the 1-2'' of new wet snow.  Above 7500' 2-4'' of new snow on a more supportable melt freeze crust.  As the day progressed the temps dropped and the snow increased.  Very minor cracking in wind loaded terrain, new wind slabs were still developing into the afternoon.  4-6'' of new snow in protected areas, winds were moving lots of snow, visibility was very limited.  

Photo:  Small natural wet slab avalanche observed at 8am, north aspect, 35-40 degree slope, 7000', on the north face of Donner Peak just east of Snowshed Wall.

Video:  Conditions at 8200' at 1pm.

Snowpack photos: 
Snowpit videos (tests, etc): 

Mt.Judah2012-3-31 005.avi

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: 
Cooling
Wind Direction: 
Southwest
Accumulation rate: 
Greater than 1 in. per hour
More detailed information about the weather: 

Rain up to 7000' in the early morning hours quickly switching over to snow by 11am above 7500'.  Snow intenstiy increasing greatly by 2pm, 2-3'' per hour.  Winds SW strong to gale all morning into afternoon.