Pro Field Report

Basic Information

Observation Details

Observation Date:
February 15, 2023
Submitted:
February 15, 2023
Observer:
SAC - Davis
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Smiley Ck (N-E-S, 7,200'-9,200')

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced
I observed one hard slab release along a heavily wind-loaded ridge between Cabin Pk and McDonald Pk in the southern Sawtooths. Cracking was confined to ski length in very thin (10-15 cm) drifts along an exposed ridge.

Snow Stability

Stability Rating: 
Good
Confidence in Rating: 
High
Stability Trend: 
Improving

Media/Attachments

This wind slab avalanche released on a SE aspect at 9,500' near McDonald Peak in the southern Sawtooths. The slide "stepped down" to break into a deeper weak layer before coming to rest on a bench.
This wind slab avalanche released on a SE aspect at 9,500' near McDonald Peak in the southern Sawtooths. The slide "stepped down" to break into a deeper weak layer before coming to rest on a bench.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Sunny
Temperature:
5-25F
Wind:
Light , NE
New/Recent Snowfall:
HST since (2/13) = 3-4 cm @ Truck, 10-12 cm @ 9,200'

Mostly blue skies with a smattering of mountain top level clouds. Moderate NNE wind decreased to light by mid-morning. Small plumes of low density snow were streaming off the high peaks of the Boulders on the drive north but not on the way home.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Feb 14, 2023
(+/- 1 day) 		Saddle near McDonald Pk
SE 9500ft 		D1.5 HS-Hard Slab N-Natural
This wind slab avalanche released on a SE aspect at 9,500' near McDonald Peak in the southern Sawtooths. The slide "stepped down" to break into a deeper weak layer before coming to rest on a bench.
This wind slab avalanche released on a SE aspect at 9,500' near McDonald Peak in the southern Sawtooths. The slide "stepped down" to break into a deeper weak layer before coming to rest on a bench.
Report
Saddle near McDonald Pk

I had expansive views of the southern Sawtooths, W. Smokys, Smokys, and Boulders. The slide near McDonald Pk was the only "large" avalanche I saw. I did pick out a few small debris piles and a possible micro crown, but these slides were inconsequential.

Snowpack Observations

I set out to gather information on crust + facet layers on SW-S-SE and to assess the amount of new snow and slab formation since Monday.

Crusts + Facets: I Traversed a SW-S-SE facing middle elevation slope. The near-surface snowpack structure here was ugly. There are multiple crust + facet layers of varying thickness in the upper foot. None of these look good. The crusts were between 1-3 cm thick and the facets were well developed at 2-3 mm. Each of these produced ECTNs with less than 15 hits. I did not find a thick or strong enough slab to be concerned just yet, but these will be likely players when the next substantial storm arrives. Some iteration of one of these layers was likely responsible for the step-down of the wind slab observed near McDonald Pk.

(1/5) was down ~53 cm and produced repeated ECTXs on W and SE aspects but broke cleanly when prying on the block.

Wind Affect: I found 10-12 cm of low density snow since (2/13). There was a good bit of drifting in the valley bottom near the mouth of Smiley Ck and along the road on both sides of Galena Pass. This did not translate to sensitive or consequential slabs in the terrain I traveled, but I don't doubt that a few exist at upper elevations with a good fetch.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: ?
Comments: These are out there as evidenced by the slide near McDonald. I didn't get the impression that this problem was widespread, and based on snow totals and the loading patterns I encountered I'd assume they taper quickly away from ridge lines.

I did not directly encounter any avalanche problems.

Terrain Use

I skiied >35 degree E-facing slopes. I avoided SW-S-SE for ski quality.