Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
January 4, 2023
Submitted:
January 5, 2023
Observer:
SAC - Davis, David, Lundy, Preuss, VandenBos
Zone or Region:
Banner Summit
Location:
Langer Pk (All aspects, 6,500-8,500')

Signs of Unstable Snow

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

Snow Stability

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

Bottom Line

We did not observe any fresh avalanches or cracking and collapsing of the snowpack. We observed weak layers of snow in the upper 1-3 feet of the snowpack. These layers produced mixed snowpack test scores but indicate that triggering a persistent slab avalanche is possible, particularly in steeper, wind-affected terrain.

Media/Attachments

Snow pit near Vanity Summit in the Banner Summit Zone.
Snow pit near Langer Pk in the Banner Summit Zone.
Snow pit near Langer Pk in the Banner Summit Zone.
Snow pit in Beaver Ck in the Banner Summit Zone.
Large buried surface hoar at the 12/19 weak layer down 62 cm on a NE aspect in the Banner Summit Zone.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Light , SE
New/Recent Snowfall:
HST = 2 cm (overnight)

Mostly clear skies on the drive north until Stanley. Low stratiform clouds clung to the Sawtooth Crest. A thicker bank of low clouds sat over most of the Banner Summit Zone. These clouds remained for most of the day, lifting and thinning later in the afternoon to provide diffuse sunshine and a breif window of direct sunshine at the end of the day.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Pk 8922, Vanity Summit
W 8700
D1 SS N-Natural One older, small wind slab pocket was observed on Pk 8922 near Vanity Summit. None

Snowpack Observations

We set out to gather more information on upper-pack weak layers in the Banner Summit Zone. Snowpack tests produced mixed results; mostly ECTXs and ECTNs, and a few ECTPs (20-40 hits). Our most notable propagating results were ECTPs under the 12/26 crust and an ECTP on 12/19 surface hoar (details in images).

Surfaces (1/3): Light snowfall sometime on the evening of the 3rd or morning of the 4th buried a weak interface. On sunnier slopes it presented as a sun crust + small facets, on shaded slopes it was a thin humidity/fog/rime wafer capped with surface hoar. This weak layer was buried intact on all aspects sheltered from the wind and will likely be well preserved by additional snowfall today (1/5).

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: 20-70 cm
Weak Layer(s): Dec 19, 2022 (FC) Dec 8, 2022 (FCsf)
Comments: Shaded where expected. Mixed results. See photos.
Deep 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: 70-140 cm
Weak Layer(s): Nov 27, 2022 (FC)
Comments: Shaded where expected. This layer was welded to the ground on steep, low elevation southerly aspects.

Terrain Use

We traveled on skis and snowmobiles through non-avalanche terrain.