Wed, Dec 16, 2020 - 7:50 PM
Broken Top Area
Snow Conditions No Avalanche Activity
Ski or Snowboard
I took advantage of the high clouds in the morning and went to Ball Butte to look around. There was a vicious breakable crust on south and east aspects that made skiing very challenging. In wind protected areas there was about 1" of new snow over the crust. The wind was moderate out of the W to SSW and there was blowing snow at ridge tops. There were shallow wind deposits, but no wind slabs at that time.
Looking out to Broken Top I could see plumes of blowing snow at ridge tops and spin-drifts coming down the east facing slopes.
The cloud deck descended rapidly and by 12:00 Ball Butte was socked in and it started snowing. Air temperature at ridge top near treeline was -4 C (25 F).
I then went to Tumalo to check on snow layers in the upper and mid snowpack. I dug into the snow on the NW side of Tumalo at around 7200'. Throughout the upper and mid pack there were several crusts over softer/weaker decomposing fragments (i.e. old storm snow). The deepest crust was a sandwich with weaker rounded grains between. No persistent weak layers were present. Although by definition, softer snow is weaker snow, I do not expect avalanches to initiate on any of the crust/softer snow combos. Snowpack testing revealed no 'sudden' results and no propagation. See photo and structure profile below.
There was also a breakable crust on the west side of Tumalo, but slightly less vicious than what I found on Ball Butte.
With sustained westerly winds and new snow coming Wednesday night into Thursday, I expect wind slabs to build on lee slopes near and above treeline.