Icy crusts on Castle Peak

Location Name: 
Castle Peak
Region: 
Donner Summit Area
Date and time of observation: 
Tue, 12/04/2012 - 13:00
Location Map: 
United States
39° 22' 0.1992" N, 120° 21' 18.6228" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

The snowpack in this area show similar characteristics to other recent observations along the Sierra Crest. The upper pack consists of a mix of thick slowly refreezing rain crusts and consolidated snow. A firm and mostly supportable frozen rain crust existed on the surface on all aspects above 7400 ft today. As of 2 pm it had not rained enough to melt this crust except in areas below 7400 ft. This ice crust made crampons a better choice for footwear than skis.

Near the ridgelines on windward aspects the snow had been scoured away to leave a sheet of very hard and thick ice. On the leeward sides dense firm wind slabs existed. Hand pits, ski cuts, oven sized corniced pieces dropped onto wind loaded slopes, and probing all pointed toward a stable snowpack in this area. Also no significant rain had fallen on the slopes at the time of these observations. Settlement cracks were prevalent around trees and rocks.

Photo 1: Icy crust on the snow surface at 8200 ft. This crust extended all the way to the summit of Castle.

Photo 2: Settlement cracks around a tree at around 8700 ft.

Snowpack photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Mixed rain and snow
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: 

Intermittent snow and rain and ice pellets fell from the sky between 11 am and 2 pm. Above 8600 ft most of this precip was ice pellets with a little rain. Between 8600 ft and 7400 ft it was more rain than frozen precip. Below 7400 ft it was all rain. A few short bursts of heavy precipitation occurred during this time, but in general the precip rates remained light.