Widespread surface hoar and unstable wind slab on Silver Peak.

For today's tour, I went into Silver Peak, looking for newly formed surface hoar that could persist until burial this evening and to have a look at the Dec 11 layer at a lower elevation, shallower snowpack location. The big news was widespread surface hoar. I was able to travel W-NW-N-NE-E-SE aspects and saw surface hoar ranging from 6 to 20 mm across all of these aspects. Only on the SE and W aspects did I see the surface hoar laying down by midday. I suspect the same had occurred on the unobserved S-SW aspects. On the NW-N-NE-E aspects, all indications were that this surface hoar, mostly about 10 mm in size was going to persist until burial this evening. Surface hoar covered all open slopes all the way up to the ridgetop. SW winds were destroying it in wind exposed areas, but I was impressed with how it was persisting upright in near treeline areas with only moderate wind protection.

Digging a snowpit in open below treeline terrain at 7,175' did not reveal any signs of instability or problematic failure on the Dec 11 weak layer at this particular location. Old faceted snow had undergone a good bit of rounding with minimal angulations on the snow crystals. While still weaker than the snow above or below it, substantial strength gains have occurred. Potential instability following substantial new snow loading appeared possible below the upper crusts in the snowpack. 

In more open near treeline and above treeline terrain blowing and drifting snow was obvious along with wind slabs. I was able to get into a safe spot on the edge of a wind slab and poke at it with my ski tip, creating a shooting crack. This wind slab was not particularly large at 1-2 feet deep max and tapering quickly downslope, but it was certainly unstable.