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Missoula Avalanche

Professional Observation

Basic Information

Observation Details

Observation Date:
February 20, 2022 - February 20, 2022
Submitted:
February 23, 2022
Observer:
WCMAC - Jane Quinn
Zone or Region:
Central Bitterroots
Location:
Mt. Fuji, Lolo Pass

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced
Isolated persistent weak layers are becoming more stubborn in snowpack tests, but due to their average depth of 66 cm (26") the consequences of triggering an avalanche are greater.

Snow Stability

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

Bottom Line

Our January 9th persistent weak layer appears to be healing, but we were able to get fracture initiation and propagation on NW and S aspects. It is still worth investigating and performing and extended column test before committing to slopes with consequential features like cliff bands and steep gullies.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
32 F
Wind:
Light , SW

Winds were not as strong as forecasted, and temperatures did not get above freezing as predicted. Precipitation varied from none to moderate.

Snowpack Observations

CT 24 SP down 65 cm on 3-4mm rounding facets
ECTP 22 on same layer on south aspect at 5740 elevation
ECTN 22 on same layer on northwest aspect
RB 5 on same layer on northwest aspect

Avalanche Problems

Persistent weak layer from January 9th ranging between 55 to 65 cm (26") in depth.

Terrain Use

Our mindset was status quo due to the uncertainty regarding the sensitivity of the weak layer. We stuck to 30 degree slope angles in light of this.

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