Abe's Armchair
Quick report
- Collapsing
- specific
We did not experience any collapsing. Cracking was common adjacent to the skin and ski tracks below ~8,500', but this cracking did not point to a collapsing weak layer, more of a disintegration of the very weak snowpack that exists here.
Weather
- Cloud Cover
- few
- Wind Loading
- previous
- Snow Avail For Transport
- small smounts
The day dawned mostly clear with a few bands of high clouds here and there. Skies remained this way for much of the day, with a thickening band of high clouds on the western horizon in the afternoon. Wind speed picked up in the afternoon, blowing steady at the low end of moderate for at least several hours. Valley bottom temps were inverted, but not terribly cold, starting the day at an estimated single digits to teens F. Temps were mild above the level of the inversion (estimated upper 20s to low 30s F.
Snowpack
Full-depth faceting continues and is particularly pronounced at elevations below the level of the inversion. There is essentially no slab on most slopes below ~8,500'. Here, the main hazards are related to lack of snow coverage, the challenge of skiing/surfing in dense, cohesionless facets, and the possibility of triggering dry loose "facet-lanches" on steeper slopes. The original stratigraphy of the snowpack is still apparent/obvious here, but the strong over weak structure has just turned into one big weak layer. If the snowpack were loaded in its current state, I'd expect avalanches to be failing at various interfaces and gouging down and entraining much of the very weak snowpack. Above the level of the inversion, the slab still has some strength, but this is decreasing by the day. Here, the snowpack remains ski supportable but it is fairly easy to push your poles all the way to the ground.
Dug on a NE-facing slope at 8,600':
HS: 55-60cm
11/30 weak layer: down 45cm, produced ECTNs with hard force (24 and 26). The initiated fractures on this weak layer did not even extend to the edge of the shovel. Subsequent tapping on the middle of the remaining block following the reported ECTNs produced similar results.
There was a ~5cm interval of 1F- snow near the base of the "slab" overlying 11/30. The snowpack above this graded from F-- to F+
There is a layer of widespread surface hoar on the snow surface. SH crystals were 3-6mm and standing tall. The distribution was originally widespread, with SH extending up to our highpoint near 10,000'. This layer has been forming for (at least) two nights an has been melted/wilted on slopes that directly face the sun and slopes exposed to the wind. It is currently well-preserved in many locations, but it doesn't look like we will be burying it anytime soon... There is a complex mix of weak snow in the upper 10-15cm of the snowpack. Dry weather with periodic small storms have formed and buried layers of weak snow that continue to facet after burial. Ambient temp and rain crusts that were present in the upper snowpack have largely faceted away on many shaded slopes.
Avalanche
I was able to trigger a small, dry loose "facet-lanche" that scoured down to and entrained all snow above the November basal crust. This was on a short section of 35-degree slope on a NE-aspect at 8,000'. This would not have buried you, but moved quickly and would have been hard to escape. In larger terrain, this slide could have become much larger. We did not observe any other recent avalanches.