Loose Wet Instabilities on Hidden Peak

Location Name: 
Hidden Peak
Region: 
West Shore Area
Date and time of observation: 
Tue, 04/18/2017 - 12:30
Location Map: 
United States
38° 58' 33.1608" N, 120° 7' 32.412" W
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Rapid warming

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

Below 7300 ft, 1 to 2 inches of new snow accumulation existed in this area and precipitation was falling as rain during the morning. Above 7300 ft, new snow amounts increased significantly reaching 8 to 10 inches of new snow on slopes above 8500 ft. Warming temperatures and solar radiation penetrating through the clouds caused the snow surface to become wet and heavy at the upper elevations.  At all elevations, this new snow rested on top of deep, unconsolidated wet snow. Ski cuts on steep slopes at all elevations and small cornice pieces dropped onto wind loaded slopes near the summit of Hidden Peak triggered large pinwheels up to 3 ft. in diameter and ski-width wide loose wet avalanches that would entrain all of the new snow.  Some minor cracking also occurred as a result of ski kicks on wind-loaded slopes. The cracking only extended 6 to 16 inches from the end of my skis. 

Photos 1 and 2: Small loose wet avalanches resulting from cornice pieces dropped onto a NE facing wind-loaded slope near 9100 ft. 

Photo 3: Loose wet instabilities on a N facing slope at around 7400 ft. 

Photo 4: Ski cuts triggered small cracking on a wind-loaded test slope near the summit of Hidden Peak.

Video: Loose wet snow sluffs near the summit of Hidden Peak at about 9100 ft. on a wind-loaded NE aspect

Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Light
Precipitation: 
Mixed rain and snow
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Cloudy with a mix of rain and snow until midday. Then on the drive home, the clouds quickly started to clear and the afternoon became mostly sunny and much warmer.