Pro Field Report

Basic Information

Observation Date:

January 29, 2023

Submitted:

January 30, 2023

Observer:

SAC - VandenBos

Zone or Region:

Sawtooth and Western Smoky Mtns

Location:

Fishhook drainage (6,400-9,600', primarily NE-E-SE-S-SW)

Recent Avalanches?

Yes

Cracking?

Isolated

Collapsing?

Isolated

Isolated cracking in new snow where it had warmed up in the sun and was sitting on an icy crust. Avalanches observed refers to loose snow avalanches that happened during both during the storm and as a result of direct sunshine this morning.

Stability Rating:

Good

Confidence in Rating:

Moderate

Stability Trend:

Steady

Advanced Information

Cloud Cover:

Clear

Wind:

Light , N

New/Recent Snowfall:

10-12cm at Ranger Station, 15-18cm at upper elevation

Cold and clear all day. Temps felt like they were dropping through the day and definitely plummeted around sunset. Winds generally calm to light in the terrain I was in, with occasional plumes of snow visible on the high peaks. It wouldn't take much wind to move the snow on the surface.

Avalanche Observation Comments:

I observed a number of small loose snow avalanches that involved only the new snow. These failed both during the storm and this morning under the influence of the sun (solar-initiated dry loose). I also observed quite a bit of earlier wet loose activity, likely from 1/21? Unsure on exact timing. Some of these appear to have found a weak layer to flank out on, likely 1/5.

15-18cm of fresh snow in upper elevation terrain. About half of this fell with the first storm wave on Friday and about half on Saturday into Sunday. The first half of the storm snow was accompanied with a fair bit of wind, the lower density snow from the second (estimated at 5%) fell mostly straight down. On solars, this snow fell on some weak crusts that could be problematic with additional loading. There are now two obvious crusts here in the upper foot of the snowpack (1/27 and 1/13 or 18 ?).

On sheltered, shaded slopes the new snow fell primarily on FCsf. Steeper solars built some crusts today, some RadRx and some more typical MFcr. These froze quickly and looked like they'd make good future weak layers.

I dug at 8100' on an E-facing slope to look at new/old interface and character of 1/5. HS=140cm. 1/5 is down 60cm here, presented as a somewhat non-descript 1cm thick stack of near surface facets and produced ECTN 30 x 2. New/old interface (1/27) produced ECTN 2 and 4 and mid-January interface (1/13 or 1/18?) produced ECTN 10 x 2.

The mid-week wind event had a significant effect on the snowpack, eroding snow in many areas and depositing large dunes and whales in others. Effects were somewhat masked by the new snow but evidence of wind-affected snow was fairly widespread. I'm still leary of these stiff, hard drifts that built on a variety of surfaces.