Black Mountain, Red Lake Bowl - Wind Slabs and Deep Slab

SNOWPACK OBSERVATION
Black Mountain, Red Lake Bowl
Submission Info
Forecaster
Sunday, March 11, 2018 - 2:45pm
Red Flags: 
Obvious avalanche path
Black Mountain, Northeast Face
Snowpit Observations
More detailed information about the snowpack: 

Observer: d lewis
Date: Mar 11, 2018, 10:39 PM
Loc: Black Mtn, Red Lake Bowl
Lat/Lon:38.0373, -119.2735
Elevation: 11200 f
Aspect: NE Angle: 25°
Signs of Instability: Pin Wheels
Sky Cover: -SCT
Precipitation: No Precipitation
Wind Speed: Calm, subjective
Snow Depth: 137cm
New Snow Storm:86cm 
Snow Temperature 20cm:-6° C 
Boot Penetration: 5cm

Comments:

Toured into Red Lake Bowl to assess the recent snowfall (3-1 to 3/3) stability, overnight accumulation (Trace), and deep instability. Found two out of three. Overnight accumulations were disappointing, Trace. Traveled up into the upper bowl: wide variety of crusts: Wind Board/Slab on N-NE aspects above ~10500’. Any shift toward to East or Southeast , encounter melt/freeze crust of various maturity depending on solar exposure duration, elevation, and aspect. Wind Slabs present pretty much in all depressions and gullys from tree-line and above. Very sheltered terrain near tree-line on N to NE aspects still soft but very limited. Above tree-line, a mix of wind board/ slab and patches of soft wind scallops on N to NE aspects, melt/ freeze on other aspects up to 11,000’. Isolated rollerballs from favored terrain (cliffs, rock bands) up to 11,000’ on solar aspects. The roller balls quickly dissipated when reaching the coldish snowpack below the rocks. Stability test suggest deep instability, a large trigger needed but quite planner. Compression tests highlighted this weakness while Extended Column test was negative. Note – the extended column failed with moderate force when applying a shovel shear test. Surface Wind Slab/Board produced moderate compression failures (4 cm thick, CTM 12.14.16, Q2). Not reactive on ski cuts and negative on ECT. Minor Wind Slab failures (2 to 3 cm very localized) on descent where new snow had accumulated. Evidence of a large D3,R3  avalanche from the March 1-3 storm on Northeast aspect, elev. 11,100’. Crown partially obscured but appeared to be a possible full depth release, debris on the lake, scoured to talus mid and upper path. No recent avalanche activity, no whoomfing or cracking. Skiing – highly variable.  Drove up into Lundy Canyon to assess how much the lower elevation snow has reseeded, it’s reseeded quite a bit. The approach to Roadside Attractions is now nearly bare, Snow is still present on the steep N-NE aspects but sagebrush is beginning to poke through. You can now drive to the resort above the lake, 4-wheel drive is suggested. Still thin from the canyon floor to about 500’ above.  

6 Stability Tests: CT16 Q2 4cm CTN Q3 4cm Weak failure under surface wind crust . Deep layer @39 didn't fail under tapping but moderate hard shear. CT12 Q2 4cm Wind crust failing on decomposing stellar below. CT26 Q1 98cm CT22 Q1 98cm CT14 Q2 4cm

Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Static
More detailed information about the weather: 

Thin Cirrrus over the valley and off top the east. 

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