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Professional Observation

Basic Information

Observation Details

Observation Date:
December 17, 2021
Submitted:
December 17, 2021
Observer:
WCMAC - Geoff Fast and Seth Tonsmeire
Zone or Region:
Southern Bitterroots
Location:
Lost Trail Backcountry

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced
Shaded north aspects that had snow on them

Snow Stability

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

Bottom Line

Lost Trail Pass area - Generally good snowpack with 2-3 feet of new snow in the past 5 days.
However, watch for areas where early season snows persisted before this storm cycle. Mainly steeper, shaded, northerly aspect, where faceted snow shows potential for propagation 2-3 feet down.
Early season conditions persist!

Media

Facets that sit on the melt freeze crust 40 inches down. Tests were failing and propagating on this layer.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Sunny
Temperature:
-10C; 14F
Wind:
Light , S

Today, temps were cold -10C, with a slight south wind, and mostly sunny skies.
After a dry and mild fall, Montana and Idaho entered winter, with 70-100cm (2-3feet) of new snow in the past 5 days in the Lost Trail Pass area.

Snowpack Observations

The 2-3 feet of new snow in the past 5 days has settled well in most locations, however, there is a layer of concern on steeper, shaded, northerly aspects above 7500 feet. Test results showed propagation around a meter down in two study pits in 145cm snowpack. ECTP22 ↓ 103cm & ECTP28 ↓ 103cm (40").
Though generally conditions are good, keep an eye on those slopes.
Also, be aware, early season conditions persist!

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