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Missoula Avalanche

Professional Observation

Basic Information

Observation Details

Observation Date:
December 7, 2022
Submitted:
December 7, 2022
Observer:
WCMAC - Jeff Carty
Zone or Region:
Rattlesnake
Location:
South ridge of Point 6

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Widespread
Collapsing? 
Widespread
Lots of whumpfing and cracking today again, but less than Monday. Collapses are traveling further distances, perhaps due to a stiffening slab.

Snow Stability

Stability Rating: 
Poor
Confidence in Rating: 
High
Stability Trend: 
Steady

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
-8º C (18º F)
Wind:
Light , W

Overcast with flurries in the morning, no accumulation. The ceiling lifted, and clouds scattered in the afternoon.

Snowpack Observations

We dug at 7600' on an east aspect after experiencing a loud widespread whumpf.

Height of snow:
-87cm (34")

Tests:
-ECTP4 down 46cm (18.5")
-PSTend 13/100 down 46cm (18.5")
-CT3 SP down 46 cm (18.5")

The weak layer is fist hardness striated facets 2-3mm.

No surface hoar was found in this pit. It is in a wind-affected location and may have been blown over or away.

Avalanche Problems

The persistent slab problem in the Rattlesnake will remain a concern for a while. The structure is very poor and the facets are advanced. The new snow has formed a consolidated slab on top of the very weak base.

Terrain Use

We kept travel and skiing under 30º; I don't trust any steeper slopes in the Rattlesnake right now.

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