Breakable crusts, wind scouring, and melt freeze snow on Castle Peak

Location Name: 
Castle Peak
Region: 
Donner Summit Area
Date and time of observation: 
Thu, 02/23/2012 - 14:45
Location Map: 
United States
39° 21' 56.4876" N, 120° 21' 30.24" W
See map: Google Maps
US


Red Flags: 
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Today on Castle Peak the sun and above freezing temperatures allowed the top 2-3 inches of melt-freeze snow to soften on the sun-exposed SE-S-SW-W facing aspects up to 9000 ft. by 2pm. On the more shaded areas on these aspects not as much softening occurred and some areas even remained frozen. Below this soft surface snow strong melt-freeze snow existed. No significant signs of wet snow instabilities were observed.

On the NE-N-NW aspects, a breakable crust with soft snow below it existed on the sheltered slopes up to 9000 ft. On the more exposed slopes E-NE winds since the last storm had scoured away the soft snow and left a firm wind scoured surface behind. Below the surface on these aspects, the persistent crust/facet combination still exists at the base of the recent snow. Extended column tests showed that fracture propagation is becoming less likely in this layer.

Snowpit from a N aspect at 8280 ft.

Photo 1: The result of an ECT test. The fracture initiated in the facets below the crust but then only traveled halfway across the column.

Photo 2: Soft, wet surface snow on a S aspect at 8400 ft at 3 pm

Photo 3: A scoured N aspect at 8200 ft.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Light
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
East
Accumulation rate: 
More detailed information about the weather: