Wet day at Carson Pass

Location Name: 
Frog Lake Ridge
Region: 
Carson Pass Area
Date and time of observation: 
Sat, 12/01/2012 - 12:30
Location Map: 
United States
38° 41' 14.226" N, 119° 59' 0.726" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Rapid warming
Obvious avalanche path
Terrain Trap
Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Pic and 1st video: Taken at 8700ft on a test slope about halfway between Carson Pass parking and provided lat/long. 2x ECTN on storm snow density change. 2x deep tap with hard, sudden planar results on NCF down 145cm. 1x PST 85/145 (end) down 145cm. When pulling on column after PST, a clean, planar fracture appeared at the interface between 1f snow from first wave of storm cycle, and 4f snow from previous 24hrs. This interface did not present itself on the 2x ECTs. Ski cuts of test slopes in this area produced no results.

Video 2: At provided lat/long. Greater slab development due to more wind exposure and rain. 2x ECTP 12/14 SC down 50cm on fist hard storm snow under 1f and 4f slab. Watch full screen in high resolution to see distinct suden collapse.

At same elevation and aspect and near provided lat/long, 3 recent avalanches were observed. Likely natural cornice fall triggers sometime yesterday or last night. All 3 were D2 R3. Full path length (300-500ft) but not full width or depth. Failure layer storm snow, and failed to step down to deeper NCF layer, which is over 1.5m deep here.

2 other natural avalanches were observed on either side of Caples Lake with similar characteristics as described above, although closer to D1.5.

Minimal ski pen throughout day. 1cm-15cm.

Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Strong
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: 

Rain on snow = very little snow available for wind transport. Partial sky clearing and end of precip ~2pm.