Black Mountain, Red Lake Bowl Trees - Wind Slabs & Storm Slab

SNOWPACK OBSERVATION
Black Mountain, Red Lake Bowl Trees
Submission Info
Forecaster
Wednesday, March 21, 2018 - 2:45pm
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Black Mountain, Red Lake Bowl Trees
Snowpit Observations
More detailed information about the snowpack: 

 

Observer: d lewis
Date: Mar 21, 2018, 10:44 PM
Loc: Black Mountain, Red Lake Trees
Lat/Lon:38.0432, -119.2693
Elevation: 10550 f
Aspect: E Angle: 35°
Sky Cover: OVC
Precipitation: Snow, Light snowfall - 1 cm/hour
Wind Speed: Strong beaufort
Wind Direction: SW
Current Temp:-1.5°C
Blowing Snow: Moderate SW
Snow Depth: 265cm
New Snow Storm:0cm 
Snow Temperature 20cm:-1.5° C 
Boot Penetration: 55cm Stability Tests: CT2 Q1 19cm CT11 Q2 33cm CT3 Q1 19cm ECTP11 Q1 19cm CT1 Q1 19cm

Comments:  

Toured up toward Black Mountain, wanted to assess the new snow bonding and building Wind Slabs. Intended to travel up toward Frog Lake and look at the NW face of Black Mountain but altered plans in route due to snow transport. Decided to move over to more sheltered terrain above Red Lake. Throughout, strong to extreme wind transport in the Alpine with Wind Slabs forming on NW-N-NE-E-SE aspects with lots of crossloading of terrain features but no visible avalanches. However, visibility was limited for most of the time. Lower tests slopes saw fresh tender cornices with Wind Slabs directly below & cracking extending out ~6’. Hand shears were a consistent easy at all elevations with some failing during isolation. All planer, failing on preserved stellers most likely from the previous day. Column test consistently failed in a fist layer directly below the new snow at surface, sudden collapse and planar @ 19cm. Extended Column ECT11 sudden collapse, and planar at 19cm. Same as the column tests. Additional testing: ECTN24 @ 67, propagated ~1/2 the column. Additional test slopes were unresponsive. New snow was dry above 10000’, below (9700') new snow was moist but dry underneath. 

On the drive: June/ Mammoth was experiencing the heaviest precipitation. As you traveled further north, precipitation diminished to lite rain below 8000’, snow rain transition from 8000 to 8500’, snow above 9000’. Precipitation was heaviest the closer to the Crest, decreasing dramatically as you move east toward 395. Air temps varied from +1 C at 9700’ to -1.5 10700’. 

Snowcover: consistent coverage above ~9500', below thinner, becoming patchy as brush, rocks, and logs/stumps begins to poke through and the snowpack recedes. 

 

 

Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Cooling
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Weather changing throughout the day. Sky cover varied from obscured,overcast, to mostly cloudy. Winds were moderate with strong gusts from 9500' to 10, 700'. Upper elevations wind were strong to galer force with extensive wind transport on NE-E-SE aspects. Active cornice formation and Wind SLab developement. 

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