Pro Field Report

Basic Information

Observation Details

Observation Date:
February 18, 2023
Submitted:
February 20, 2023
Observer:
SAC - VandenBos (off duty), Peterson, Gall, Mawhinney
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Fishhook (6,400-9,800, primarily northern half of compass)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Snow Stability

Stability Rating: 
Very Good
Confidence in Rating: 
Moderate
Stability Trend: 

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Moderate , W

Light snowfall for most of the day, with periods of S1. Total daytime accumulation of 2-3cm. Intermittent, gusty winds blowing out of the W, with periods of relative calm and periods of sustained moderate winds. Winds were effectively transporting snow when blowing.

Avalanche Observations

Aside from active spindrifting in upper elevation terrain, we did not observe any new avalanches.

Snowpack Observations

As has been observed across our region over the past few weeks, there was significant wind "damage" from northerly winds in upper and plenty of middle elevation terrain here. Surfaces are a real mixed bag in the alpine, with a little bit of everything to be found. Icy, polished wind-board, faceting old slabs, tall sastrugi, and a good bit of soft snow as well. As you move down into more sheltered terrain the snow surface becomes more predictable, presenting as a thick stack of well-developed facets on shaded slopes and a stack of several crutst+facets on solar slopes. I would anticipate that we will see some avalanches with a persistent slab character in more sheltered terrain if we get a significant rapid load on snowpacks that look like this.

We dug on a N-facing slope at 7,800' (HS=200cm) to look at weak layers in the upper 1m of the snowpack. Layers that developed and were buried in January and February (1/5 and up) were more apparent here than where I've been seeing them in the Banner area. 1/5 was buried 55-60cm down and presented as a thick stack of rounding facets. Though visually obvious, this layer was fairly dense (4F+ to 1F-) and behaved reasonably well in stability tests, producing ECTNs with hard force. I suspect these January and February weak layers are a bit worse in the Sawtooths than around Banner, though maybe not much. Several layers were present above the 1/5 interface. These produced ECTNs in the teens and rough shears on thin, discrete layers of small facets.

Terrain Use

We felt comfortable entering steep, high consequence avalanche terrain while paying close attention to active wind loading and recently formed wind slabs.