Frozen Crusts, Moist Facets, and Wet Snow on Castle Peak

Location Name: 
Castle Peak
Region: 
Donner Summit Area
Date and time of observation: 
Fri, 01/12/2018 - 12:45
Location Map: 
United States
39° 21' 54.54" N, 120° 21' 30.6" W
US



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

A widespread firm frozen rain crust existed on all aspects up to at least 8400 ft. on Castle Peak this morning. In sheltered below treeline areas, this crust had surface hoar on top of it. The crust was ski supportable but would not support a person on foot. A thin layer of softer recent snow that rested on top of a thicker rain crust existed below the surface crust. By 1:30 pm the surface crust and the thin layer of recent snow had become soft and wet on southerly sun-exposed aspects. 

On northerly aspects, the old facet layer still exists about 25 cm (10 in.) below the surface. It still has not refrozen in some areas and it remained loose and weak where it was still wet. Observations indicated that the slab above this layer continues to gain strength and that as the snowpack continues to refreeze it should continue to strengthen. Tests targetting this layer today yielded unstable results, but observations also indicated that it may be difficult to find a place where a person could break through the hard strong snow above this layer and to initiate a fracture in it. This layer seems to exist in some areas as a loose weak layer of moist snow while it seems to have refrozen some in other places. 

Photo 1: Surface hoar on top of a frozen rain crust in a sheltered meadow @ 7600 ft.

Photo 2: ECTP failing on the moist facets below a strong slab layer on a NW aspect @ 8300 ft.

Photo 3: Frozen surface crust on a NW aspect along the ridgeline @ 8400 ft. @ 1:30 pm.

Photo 4: Soft wet snow surface on a SW aspect @ 8200 ft at 1:30 pm.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Cloud Cover: 
Clear
Air temperature: 
Above Freezing
Air temperature trend: 
Warming

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