Yost Lake Trees - Snowpack Stability & Devil's Slide Debris

SNOWPACK OBSERVATION
Yost Lake Trees
Submission Info
Forecaster
Monday, March 26, 2018 - 2:45pm
Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Yost Lake Trees
Snowpit Observations
More detailed information about the snowpack: 

 

Observer: d lewis
Loc: Yost Lake Trees
Lat/Lon:37.7570, -119.1131
Elevation: 7750 f
Aspect: NNW Angle: 25°
Signs of Instability: Wind Loading
Sky Cover: CLR
Precipitation: No Precipitation
Wind Speed: Light Beaufort
Wind Direction: N
Blowing Snow: Light SW
Snow Depth: 67cm
Boot Penetration: 5cm 3 Stability Tests: CTN 0cm CTN 0cm CT24 Q3 35cm Failed on moist rounds below. Unable to duplicate.

Comments:Toured up into the trees below Yost Lake/Fern Creek to assess the lower elevation snowpack depth and general stability, get some pictures of the Devil’s Slide debris field, and see if the northern lower elevation rocky faces were beginning to warm-up. Snowpack depth below ~7500’ is thin and becoming patchy as more logs, stumps, rocks and shrubs begin to poke through, increasing the melting further. Depth varied between 0 and ~ 30 cm (~1’). Above ~7500’, where the slope steepens and is more shaded, snow depth increased to ~50 cm to ~150cm depending on elevation, aspect, and whether the slope is open, sparsely treed, or mature forest. The snow from 3/21-22 was quite wet at the lower elevations and has set up into a supportive melt/freeze crust over moist rounds from the earlier March snow cycles. On steep terrain this could be a slide for life concern. No real failures that could be reliable duplicated. Northern aspect of Carson Peak remained cold, with no noticeable Loose Wet activity. The debris field in Devil’s Slide was too big to fully capture from the perspective but the pictures show the depth of toe of the avalanche. The new snow (2 to 5cm) was light and peels of easily from the underlying melt/freeze crust. The new snow remained cold and dry above ~7500’, especially where the slope is shaded or steep. Lower angle sun exposed slopes varied from a light delicate melt/freeze crust to wannabe corn snow. 

Devil's Slide - debris was easily 25' (> 7.5 Meters) and covered an exceptinally large area.    

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Devil's Slide, Debris Field
Devil's Slide, Debris Field Too
Weather Observations
Blowing Snow: 
Yes
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Northwest
Accumulation rate: 
More detailed information about the weather: 

Light winds at the lower elevations. Based on wind transport, moderate at ridgetop. 

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