Quick report
- Red Flags
- Recent Avalanches, Poor Snowpack Structure
Went up Thomas Fork to look at the snowpack structure at the low and mid elevations. There was a serious accident in this drainage this past Wednesday, December 14 and we looked at the snowpack on an adjacent slope with a similar aspect and elevation. Full propagation with extended column (ECTP24) failing down in the layer of faceted snow that was the weak layer in Wednesday's accident. (Grom score of 5.)
Another pit at 8,600' on a NW aspect was ECTP22, again failing down in the November facets.
The layer of faceted snow was weak where we were traveling, Fist (F) or 4F- hard, with stronger 4F or 1F slab on top of the facets.
There is spatial variability of this PWL throughout the central Wasatch: on Saturday I was finding the faceted layer to be 4F and sintering (gaining strength) above 8,000' in Big Cottonwood. My partner was finding the facets also 4F in Porter Fork. The facets we were finding today were much weaker.
As we move towards increasingly stability, there are still some areas where triggering a slab avalanche on the facets are still possible, especially below 8,000'
Photos of pit profile on a slope adjacent to where Wednesday's avalanche accident occurred.
Snowpack
- Instability Comment
- <p>We were getting full propagation with extended column tests on pits at 7,200' and 8,600' failing down 60 cms in the layer of mid-November facets.</p>
Some weak snow developing at the surface: surface hoar, near-surface facets, and radiation recrystallization on some solar aspects. The cold temperatures the past few days has preserved the stellars from this past week's storm so there is plenty of weak snow in the top ~30 cms of snow.