Pro Field Report
Basic Information
Observation Details
Observation Date:
December 22, 2022Submitted:
December 22, 2022Observer:
SAC - Jon PreussZone or Region:
Sawtooth and Western Smoky MtnsLocation:
Bench Lakes (E-S-N; up to 7800')Signs of Unstable Snow
Recent Avalanches?
YesCracking?
IsolatedCollapsing?
IsolatedSnow Stability
Stability Rating:
FairConfidence in Rating:
ModerateStability Trend:
ImprovingBottom Line
Yesterday's wind event caused a smaller natural cycle in the Sawtooths than observed in the Wood River Valley. Dry sugary facets still remain at the bottom of the snowpack in middle and lower elevations. They are close enough to the surface, that I was getting collapsing in untouched areas. There was less collapsing as I gained elevation and the slab become thicker in size.
Advanced Information
Weather Summary
Cloud Cover:
OvercastWind:
Light , WNew/Recent Snowfall:
HST: 20cm (above ~7200')Mostly clear this morning until high clouds came overhead around 1300hrs. It was cold and overcast for the rest of the day.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
|---|---|---|---|---|---|---|---|---|---|
| 1 |
Pk. 9934' (above Farley Lake) E 9700 |
D2.5 | HS | N-Natural |
|
I intentionally kicked a small wind slab on the way up the moraine. It entrained facets on an east aspect around 7200'.
There were numerous D1 avalanches along the roadside of Galena Pass. Most appeared to fail at the new/old interface. One near Twin Bowls may have been remote triggered by tracks above 15' above them.
Snowpack Observations
Dug many snow pits today to see what the sensitivity and distribution is of our weak layers. The layer of concern was the November snow (11/27), which was pushing depth hoar (chains of 3-5mm) size in lower elevations and facets (2-3mm) into the middle elevation band. The grains were dry in the lower elevations and most talkative with some long traveling collapses on low angle sunny slopes. I found very spotty surface hoar on a East slope at 7500' but it was fully embedded with the slab above and not the issue.
The new/old (12/19) mostly displayed resistance planar character and isn't likely to stick around for long. Even where it sits on top of a crust, it is fairly bonded to those surfaces. There wasn't a distinct (12/8) layer in any of my pits, some showed near surface facets being compacted with ECTN results.
7700' South HS: 56cm
There were 3 melt freeze crusts with facets building in between them. The most fragile layer was down 37cm with near surface facets on top of it. ECTP 20 down 37cm
7700' North HS:100cm
The slab was 62cm thick with 1F on top of 28cm thick 4F- facets (2-3mm). ECTN29 x2 on 12/8 CPST 32/100 (end) dn 62cm.
7500' Southeast HS: 83cm
The slab was 57cm thick with 1F on top of 15cm thick F facets (2-3mm). ECTP18, ECTP27 x2
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Persistent Slab
|
|
Layer Depth/Date: 72cm/1127 Weak Layer(s): Nov 27, 2022 (FC) |
|||
Wind Slab
|
|
Layer Depth/Date: 30-60cm/1221 Comments: I found hard and soft slabs in isolated terrain features of lower elevation. |
Although I was able to get some large collapses on low elevation souths, it seems unlikely to have this problem on the slopes steep enough to slide. There was a healthy amount of sage brush sticking out and I don't think the November snow is connected enough. I wasn't able to investigate south facing slope that were steeper in the lower elevation.
Terrain Use
I haven't been into this area yet this season, so had an assessment mindset. I avoided avalanche terrain.