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Missoula Avalanche

Professional Observation

Basic Information

Observation Details

Observation Date:
December 29, 2021
Submitted:
December 30, 2021
Observer:
WCMAC - Ryan Sorenson
Zone or Region:
Central Bitterroots
Location:
Camas Lake

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced
Cracking on small wind-loaded test slopes isolated to directly under skis in the top 4 to 6 inches. Small wind slab triggered mid-slope on steep rollover at 7,400 feet.

Bottom Line

We toured in the Camas Lake area, looking at the extent of wind slab formation and if reactive persistent grains exist.
• Snow surfaces became more wind-hardened above 7,400.
• Wind slabs on small wind-loaded test slopes were stubborn to trigger, and minimal cracking was isolated directly under skis.
• Looking across the canyon south and easterly aspects were scored due to stronger funneled winds. North and westerly aspects show signs of wind loading.
• Persistent grains were present near the base of the snowpack and were not reactive in column tests.
• We accidentally triggered a small soft wind slab avalanche on a steep rollover mid-slope at 7,400 feet on a north aspect. This avalanche was harmless in size, but similar slides could become more of an issue with more wind loading, slab hardening, and depth.
• Plenty of snow is available for wind transport.

Media

Advanced Information

Weather Summary

Cloud Cover:
Mostly Sunny
Temperature:
10°
Wind:
Light , W

Winds were calm for most of the tour. We experienced a light westerly breeze at 8,000 feet on the ridgeline. Various cloud layers hung below 7,000 feet with clear skies above. It was lightly snowing as we toured through lower elevations.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Today Camas Lake
N 7,400
D1 SS I-New/Old Interface 6 inches AS-Skier
u-Unintentional
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