Professional Observation
Basic Information
Observation Details
Observation Date:
February 17, 2020Submitted:
February 18, 2020Observer:
SAC - VandenBos (off duty)Zone or Region:
Sawtooth and Western Smoky MtnsLocation:
Stanley Lake CreekSigns of Unstable Snow
Recent Avalanches?
None ObservedCracking?
None ExperiencedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
FairConfidence in Rating:
ModerateStability Trend:
ImprovingBottom Line
Significant amounts of accumulated new snow in upper elevation terrain below steep cliffs and in soft drifts along ridges kept me out of these areas.
Advanced Information
Weather Summary
Overcast in late morning with skies partially clearing late in the day. Calm to light northerly winds. 10-12cm new snow at highway level with closer to 20cm at upper elevations. Intermittent periods of S1 flurries, often with graupel, produced 1-2cm of new snow today. Mid teens F at highway, estimated in single digits F at upper elevations.
Avalanche Observations
It was hard to be certain but looked like some small (D1) storm/spindrift slabs had failed below steep cliffs in a few places.
Snowpack Observations
15-20cm of new snow was sitting on a variety of firm surfaces, none of which seemed to be reactive, based on rough hand shears and the lack of observed avalanche activity. If you were going to find somewhere to get into trouble today it would have been in steep upper elevation terrain where spindrift off cliff bands or mid-storm winds had stacked considerable amounts of extra snow. I'd expect this sort of instability to be short-lived, but yesterday didn't feel like the day to go find out. The several hour wind event that took place late in the day on 2/16 had built a thin, 4F+ to 1F hard, wind skin in more open upper elevation terrain.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Wind Slab
|
|
Felt stubborn to unreactive today, but with recency of loading I didn't need to go find out for myself in steep, high-consequence terrain. |
No direct observations on deep persistent problem. No reported activity locally on this layer since deep slab cycle in Sawtooths in mid-January. Loose snow issues could be a problem tomorrow with more direct sun, but cold temps could mute the problem.
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