Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
January 11, 2020
Submitted:
January 11, 2020
Observer:
SAC - Martin Stefan
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Mushroom ridge

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced
Soft slabs in the new snow avalanched on the road cuts at the pass. Very isolated cracking when stomping on fresh cornices.

Snow Stability

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

Bottom Line

The usual weak layers from early december and New Year's are present from mid elevation and up, but the lack of cohesive slab makes them unreactive. However, where the wind has done work the tune changes quickly. An ever so slight stiffening in the overlying slabs quickly brings back snappy results on the buried weak snow from New Years, now some 50cm down. Even if it looks better here than in other areas, it is still not an easy game to play.

Advanced Information

Weather Summary

Cloud Cover:
Obscured
Temperature:
teens
Wind:
Light

Light winds at mid elevation, about 8" of new snow at 7000'. Light snowfall until early afternoon, accumulation not more than a couple of inches.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
Numerous Road cuts on Galena Pass
SE 8600'
D1 SS I-New/Old Interface 20cm est N-Natural Most road cuts on the way up to the pass had avalanched, looked like soft slabs with just the new snow.
Plow-triggered avalanche near the top of Galena Pass, SE aspect at 8,700'. Based on crown depth, this slide failed within the new snow.

Snowpack Observations

At mid elevation around 9000' both SW and SE non wind affected slopes HS around 110cm 12/7 (approx 60cm down) and 12/31 (approx 40cm down) are both present, and so is DH, mostly without crust. Test results were very indecisive, with a couple of high 20s ECTPs on DH and 12/31, but also ECTX on the same layers, and PST arr. Slab under 12/31 is faceted to various degrees, and not very cohesive. Storm snow on top also not very cohesive but shows subtle signs of creating a soft slab and gives up to 10 cm of propagation before arr on pst.

At 9500' on an ever so slightly wind stiffened slope (would still qualify as powder, but maybe a little more creamy than blower) HS 115cm 12/31 50cm down under 10cm windskin, 12/7 75cm down, snappy ECTP12 q1 on 12/31.

I did not venture any higher, but chances are that the wind has stiffened the slab enough both above and below 12/31 that it would become a concern.

Storm slab as such was not very responsive, but slides on the pass indicates that it might be elsewhere.

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: 50-65cm (12/7), 30-50cm (12/31), DH
Comments: Distribution of this patchwork of weak layers is very widespread in the area, but reactivity varies from stubborn at mid elevations S 1/4 to reactive at higher elevs. Did not investigate other aspects today.

Terrain Use

I avoided avalanche terrain except for short crossing of short runt out in low elevation sheltered terrain.