We did not see any red flags while we were out, but there were quite a few larger recent avalanches that had released recently. (See Andy Moderow's ob yesterday for more- but this includes activity on Pete's North, Lipps, and the south end of Seattle Ridge).
Observation: Turnagain
Location: Cornbiscuit
We toured around Cornbiscuit, digging a bunch of pits to investigate the problematic Thanksgiving crust/facet layer. We dug on north, northwest, west, and southwest aspects and got mixed results in our stability tests. Some test results were showing poor stability while others did not show any concerning signs. The poor structure was consistent throughout, with the weakest snow either right below or directly above the top of the crust/facet sandwich.
Observer Comments
Weather
Clear, calm, and cold- especially down in the parking lot. -8 F when we were gearing up this morning, but there was a strong inversion and temps were a cozy 14 F at 2000'.
Snow surface
A little over a foot of soft snow on the surface. The surface snow is turning to facets with the continued cold and clear weather. Some slopes had a very thin wind skin right on the surface.
Snowpack
Our test results varied from snowpit to snowpit, but the poor structure was consistent. The Thanksgiving crust/facet layer is anywhere from 4-6" thick, with multiple alternating layers of thin crusts and facets. The weakest snow is directly above and below the uppermost crust. For the tests that did propagate (poor stability), the weak layer that was failing was just below the upper crust.
This layer of concern is tricky. It has produced large avalanches at the south end of Turnagain Pass, and in Girdwood. It is also showing poor stability in some snowpits. On the other hand, there are a ton of tracks in steep terrain around the pass, so it is clearly a stubborn layer and maybe not a problem at all locations. There's just not a great way to know which slopes are stable and which ones aren't until you trigger a big avalanche.
Snowpit on a NW aspect at around 2000'. This structure was consistent in our pits today, and most of the pits we've been digging for the past week or so. Photo: Andy Moderow. 12.18.2022
Snowpilot profile from one of our pits today. Again, structure was consistent in our four pits. 12.18.2022
This deeper pocket on the north side of Lipps looks like it was triggered by a shallower avalanche in the new snow from last week. 12.18.2022
Plenty of tracks in steep terrain in Superbowl without any skier triggered avalanches. Debris off the north side of Cornbiscuit in the foreground, from natural acitivty during last week's storm. 12.18.2022