Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
January 24, 2023
Submitted:
January 24, 2023
Observer:
SAC - Scott Savage
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
E Fork Baker Ck - Fox Peak (6700-9100', mostly 8600-9100': all aspects but minimal travel on S, N, or NE)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
None Experienced
Cracking was in one of the many hardslabs (wind) I stomped on - about 1 foot deep, 20 feet in front of me. See photo of older avalanche, guessing Jan 11-15.

Snow Stability

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

Bottom Line

Recent and ongoing winds formed hard slabs up to about a foot thick just below exposed ridgelines around 9000'. The slabs did not extend far below the ridgeline and were difficult to trigger/crack, but they were very hard and hollow sounding + feeling. The weak layers buried 1-2 feet deep existed on all aspects near 9000' and did not look great, but they did not produce any unstable results in snowpack tests.

Media/Attachments

Recent northerly winds formed hard wind slabs up to a foot thick at exposed ridgelines near 9000' on Fox Peak. The fresh slabs were difficult to trigger, but Scott was able to get one to crack about 20 feet out from his skis. The slabs only extended 10-30 feet below the ridges, but the slabs' hollow sound and feel was "creepy".
Snowpit on an east aspect on Fox Peak near 9000'.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Temperature:
Teens F
Wind:
Strong , N
New/Recent Snowfall:
HN=3-8cm in recent days (since the road was groomed)

Skies began clear around noon and were obscured with S-1 by 4 PM. Winds were moderate-north before 2 PM, strong-north from 2-4 PM, and decreasing to moderate from 4-4:45 PM. The afternoon wind event drifted the road (down to near 7000') with snow, scattered pine needles and boughs all over, and dumped a lot of tree bombs. Large plumes were coming off Osberg Ridge, but the wind-blown snow appeared to be mostly sublimating. The wind has transported most of the "easily-transported" snow.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 E Fork Baker Ck
N 8200
D1.5 O-Old Snow U-Unknown May have been skier triggered, remotely?
Small, older avalanche that released on a north aspect near 8300' in the E Fork of Baker Ck drainage.

Unknown release date on the pictured slide. I may add additional photos of old avalanches Wed morning, Jan 25, after reviewing my photos.

Snowpack Observations

I focused on the highest terrain (near 9000') that was wind-sheltered enough to preserve weak layers and not develop wind slabs but exposed enough to see subtle wind effects. The structure at 1/5 and 12/19 remains concerning, but all ECT results were ECTN or X on these individual layers. Above 8600', HS=120-170cm.

The most notable observation is how weak the upper 15-25cm of the snowpack is: a mix of SH, FC, and delicate PP/DF with a thin razor crust on the top on S-SW.

NW 8980' (see photo below): HS=160cm, 1/5 down 35cm (3-4mm SH and some FC underneath a thin degrading wind/rime crust), 12/19 down 65cm (3-8mm SH, mostly laying down but some upright). ECTN22,21@30cm down (a thin FC interface just above 1/5), ECTN24@35cm down (1/5).

E 9000' (see photo above): HS=157cm, 1/5 down 32cm (FC, SH shards), 12/19 down 62cm (SH, not upright). ECTN17,18 @ down 32cm (1/5), no results on 12/19.

SE 9050' (SnowPilot profile coming on Wed, 1/25): HS=130cm, 1/5 down 30cm (SH shards with nice FC above), 12/19 down 65cm (SH 3-5mm not upright). ECTN19,18 @down 30cm (1/5), ECTN28 and no result @down 65cm (12/19).

SW 8950' (see photo below): HS=155cm, 1/5 down 30cm (FC above a crust), 12/19 presented as 2 layers down 65-72cm. ECTN20,21@down 30cm (1/5), no ECT results on any other layers.. Multiple layers just above and below 12/19, as well as the top of 11/27, produced clean shears when prying on blocks after doing ECT tests.

Snowpit on a NW aspect on Fox Peak near 9000'.
Snowpit on a SW aspect on Fox Peak near 9000'.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 30-35cm
Weak Layer(s): Jan 5, 2023 (SH) Dec 19, 2022 (FC)
Comments: Shaded area indicates where I traveled and observed persistent weak layers at the 1/5 interface (SH and FC) and 12/19 interface (mostly SH except FC on SW aspect). All test results on 1/5 were ECTN 17-24. On 12/19, I got a single ECTN24 and 7 x "no results".
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: <30cm
Comments: Shaded area indicates where I encountered recently formed hard slabs. They were P to K hard but only extended 10-30 feet below ridgelines. Of the 6 or 7 I stomped on, only one of them cracked.

Terrain Use

I was traveling solo and stayed out of all starting zones. I did not travel in any avalanche path tracks other than while on the road.