VA Lakes - Strong winds and New sensitive windslabs

SNOWPACK OBSERVATION
South Peak
Submission Info
Forecaster
Wednesday, January 24, 2018 - 12:00pm
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
38° 2' 23.4996" N, 119° 15' 15.93" W
Snowpit Observations
More detailed information about the snowpack: 

Very windy day today everywhere!  Lots of visible wind transport at mid to upper elevations all along 395, with even a tractor trailer being blown off of 395 onto its side near mono lake (really hope the driver wasn't too badly injured!).  

Toured up from VA Lakes Rd up to ~10,800' on South Peak in search of sensitive new wind deposits.  Lots of wind from the south to southwest, resulting in turbulent wind transport across north facing slopes.  Across Mt Olsen this was mostly West to East, across the upper slopes of VA Peak, it was mostly East to West!  At the summit of VA peak, it was coming right over top from the south onto the north.  See attached video of transport across Mt. Olson.

Despite lots of snow likely sublimating into the atmosphere, there were definitely areas where it was being deposited into sensitive wind slabs.

Up to ~10,500', wind slab pocket were extremely patchy, small and isolated.  See first video of hand pit failing upon isolation on NNW facing slope at 9850'.  1-3" of finger hard snow ontop of 4 finger snow.

At 10,700', ~2/3 of the way up S. Peak from the saddle between Olson and S. peak, windslabs became much larger and widespread.  Still obvious areas were wind was stripping, and wind was depositing, and quite variable, but in these deposit areas we had many shooting cracks going out across the gullies up to 10meters long, and handpits failed with very easy force or isolation, and were denser and thicker.  See attached video of solid 6" pencil hard slab (ski penetration=0cm) lying over 3-4" of fist hard loose snow (which was ontop of VERY hard firm old bedsurface from slides that occured during the snow storm/wind event on Jan 9-10).  These were on slopes of ~32-34 degrees.  I have little doubt that if these slopes were 5degrees steeper, or unsupported, D1-2 avalanches would have resulted.  

Lots of loose facets in the mid-pack.  At 9850', one test pit on NNW facing slope showed 70cm total snow depth, with MANY alternating layers of melt freeze and facets.  Around rocks above 10,500' were 3mm+ well developed facets.  At 10,800', at 1:30pm: airtemp=-3.5deg C.  

Overall impression:  Be on the lookout for fresh sensisitive hard windslabs!  Especially on slopes >35degrees!  With significant new snowload that could come in tonight and tomorrow, deeper facet layer failure could become a concern.    

 

Snowpit videos (tests, etc): 

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