Rapid Warming on Andesite Ridge

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of observation: 
Fri, 02/28/2014 - 10:00
Location Map: 
United States
39° 20' 38.22" N, 120° 21' 15.696" W
See map: Google Maps
US


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

Snowing S5 at 0830 this morning then the abrupt end of precipt about 0930.  Fifteen minutes later the sky cleared and the sun instantly changed the snow surface layers turning them heavy and sticky.  Trees started shedding snow almost immediately.  No cracking or collapsing observed, no recent avx activity either.  HS just on the lee of the ridge about 180 cm with top 50-55 cm new snow.  Moderate snow transport by W winds also ceased with the abrupt warming though winds continued.  Snow surface was now too damp and resisted wind transport.  First video shows a few shear planes within the new snow, second shows breaks below the old snow surface in the crust complex that occupied the previous top 10-15 cm of the snowpack. By the time I skied out of here (1045) clouds had moved back in and graupel was falling.    --R.Osterhuber

Snowpack photos: 
Snowpit videos (tests, etc): 

Breaks in new snow, Andesite Ridge 20140228

Break in crust below new snow, Andesite Ridge, 20140228

Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Warming
Wind Direction: 
West