Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
January 13, 2020
Submitted:
January 13, 2020
Observer:
SAC - Martin Stefan
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
Triple Peak

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
Isolated
Lots of cracking and collapsing on wind-stiffened snow at or near ridge top.

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
Moderate
Stability Trend: 
Worsening

Bottom Line

In this area the wind has done work drifting new snow into soft wind slabs that lie either directly on top of a thin and weak snowpack at low to mid elevations or on a combo of a hard windbuff under a few inches of soft, low density snow from 1/12 on higher elevation leeward slopes and ridgelines. This windslab is soft enough to be sensitive to a single skier, but stiff enough in places to propagate collapses and shooting cracks.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Temperature:
teens
Wind:
Light , S

Light to moderate cold wind from south. The wind tonight has caused considerable wind transport, even in the valley and at low to mid elevations.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Trail Creek
N 6800'
D1 SS I-New/Old Interface N-Natural Small slide probably triggered by cornice drop. Despite considerable wind loading this was the only activity I saw.
D1 avalanche in Trail Creek, N aspect 6800' approx. Probably triggered by cornice drop due to wind loading.

Drove up to Galena Pass and back this morning. Glassing the boulders I could not see any activity, but visibility was less than ideal. No slides on the road cuts by 11AM. Plenty of wind transport from W over and through the pass.

Snowpack Observations

In this area snowpack comes in 3 varieties:
1: on solars, a lot of sage is still poking through. There are potential for some cross-loaded features to hold more snow, and fall in cat. 2.

2: Low and mid elevation shadies: 30-50cm of weak faceted snow with a fresh 30-40cm soft wind slab on top. This combo seems not to be very reactive yet, but more loading or wind could change that. There is an interface layer of FCsf in places, but without much of a bed surface I see it as a potential future problem and not an immediate concern.

3: High elevation and wind-exposed mid elevation shadies: Various kinds of wind buff, a thin layer of soft, low density storm snow from 1/10 with a denser 30-40cm F-4F wind slab on top, or a thinner but stiffer variation of the same. This combo is quite reactive giving shooting cracks up to 10m and lots of small to mid sized collapses. There is also potential for faceting in the 1/12 snow considering the density differences involved, might be something to keep in mind going forward.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
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: 1/13
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: 1/13
Comments: Wind slab at low to mid elevs almost omnipresent, but not reactive to my tests, probably it's still too soft and the weak layer too thick (old snowpack)

Note that these observations are only for the Lake Creek area, it is safe to assume that our old persistent weak layers have not disappeared where they have been present previously, but rather are straining under even more load than before.

Terrain Use

I avoided avalanche terrain.