Deep Wet Snow on Castle Peak

Location Name: 
Castle Peak
Region: 
Donner Summit Area
Date and time of observation: 
Thu, 04/07/2016 - 11:00
Location Map: 
United States
39° 21' 20.1744" N, 120° 20' 27.0528" W
US


Red Flags: 
Rapid warming

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

Deep unsupportable wet snow already existed on many E-SE-S aspects up to at least 8600 ft. by 11:00 am on the south side of Castle Peak today. The W-SW aspects remained supportable until about 12:30 pm above 8400 ft. before they too held deep wet snow at all elevations. Stepping off of my skis on the E-SE-S aspects resulted in sinking into boot top deep wet snow as early as 10:40 am with similar conditions forming on the W-SW aspects by noon. Ski kicks triggered loose wet avalanches on E and SW facing test slopes that entrained 15 to 20 cm of wet snow at 11:00 am and 12:30 pm respectively. Northerly aspects held more supportable melt freeze conditions with 2 to 5 cm of wet snow resting on top of supportable melt freeze crusts at noon. A large UPS truck sized piece of cornice had broken and slid down a NE facing slope and entrained some wet snow as it slid. This cornice failure looked recent and likely occurred on April 6th. the remaining cornices had large cracks forming on the ridges behind them. 

Photo 1: Skier triggered loose wet avalanche on a 38 degree, E facing slope at 8100 ft. at 11:00 am

Photo 2: Boot top deep wet snow on a SE aspect at 10:40 am. 

Photo 3: The cornice where the UPS van piece broke away from above a NE aspect at 8600 ft. 

Photo 4: The track of the sliding cornice pieces. 

Photo 5: Cracks behind the remaining cornices. 

Snowpack photos: 
Snowpit videos (tests, etc): 

Skier Triggered Loose Wet Avalanche on Castle Peak

Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Light
Air temperature trend: 
Warming
Wind Direction: 
East
More detailed information about the weather: 

Thin cirrus clouds moving into the area in the afternoon