Close

Professional Observation

Basic Information

Observation Details

Observation Date:
January 12, 2020
Submitted:
January 12, 2020
Observer:
SAC - Martin (off duty), Sam, Josh
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Senate

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
Isolated
Collapses on DH under wind stiffened snow on ridge line. Cracks going down through wind slab to New Years weak layer in less scoured but still wind affected areas.

Snow Stability

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

Bottom Line

Even very subtle wind effect that might not even be noticeable when on skis is clearly picked up by our buried weak layers, human triggered avalanches are definitely in the cards at higher elevations and we steered clear of any avalanche terrain.

Advanced Information

Weather Summary

Cloud Cover:
Obscured
Temperature:
teens
Wind:
Light , SE

Very light snow all day, picking up towards the afternoon. A trace to an inch of snow overnight.

Snowpack Observations

At higher elevations the snowpack was very variable. In previously wind scoured ridgetop location it was just the storm slab on top of 20-30cm DH, or 10cm DH + MFcr. These are obviously quite touchy and more often than not gave collapses and some shorter shooting cracks, but it seems mostly isolated to a narrow band along ridgetop. Where it gets a little fatter and was less scoured before 1/10 we got cracks shooting a few meters, failing of 12/31


9700' SSW lightly wind affected HS 125cm HST 30cm
11/26@ 25cm DH to GND
12/7 @ 48cm FC no crust
12/31 @ 62cm FC
64-90cm 4F RG under new storm snow. Under 12/31 various degrees of faceting, around 4F. ECT just bangs through the snowpack, with ectn on the weak layers. PST in the 20s on all the PWLs, they seem not very happy right here.

I would not ski any avalanche terrain that the wind has touched, however gently it might be. New loading cycle beginning this afternoon is not going to help matters either.

9700' SSw Senate. 11/26, 12/7 and 12/31 all sensitive to PST. Snowpack here essentially doubled in the last 12 days.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
 Layer Depth/Date: 11/26, 12/7, 12/31, 30-105cm
Unreactive on s1/4 mid elevation terrain where slab is faceted, reactive to touchy everywhere the wind got to it

Terrain Use

We avoided avalanche terrain

Close