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Missoula Avalanche

Professional Observation

Basic Information

Observation Details

Observation Date:
February 25, 2022 - February 25, 2022
Submitted:
February 25, 2022
Observer:
WCMAC - Todd Glew
Zone or Region:
Central Bitterroots
Location:
Gash & Bear Creek

Signs of Unstable Snow

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

Snow Stability

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

Bottom Line

Travel was from 4800' to 8200' in the Gash Creek drainage. Earlier this week, I was up at the Gash and found a persistent weak layer (PWL) buried about 3' down propagating in extended column tests (ECT). The PWL was still reactive in snowpit tests today. I dug a snowpit at 7000' on a north aspect and got ECTP19 failing on facets, sitting on the top of a slick melt-freeze crust, buried about 3' down. In the Bear Creek drainage, I saw two large natural avalanche crowns on similar aspects and elevations to where I got propagation in the ECTs. I would assume that these avalanches failed on the same PWL as I saw in the snowpits. I discovered that this PWL problem is most likely between 6500'-9000' on all aspects besides SW, S, and SE.
Below are some key points from today:
• 3' deep hard slab avalanches are possible on 35º+ slopes facing E, NE, N, NW, and W between 6500'-9000.'
• Triggering wind-slab avalanches in wind-exposed terrain above 6500' is possible.
• The cold temperatures and steady light winds helped the snowpack to stay dry above 6500' on all aspects.
• Surface hoar was found on wind protected slopes on all aspects besides south.

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Advanced Information

Weather Summary

Cloud Cover:
Clear
Wind:
Light , NW
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