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Professional Observation

Basic Information

Observation Details

Observation Date:
April 5, 2020
Submitted:
April 6, 2020
Observer:
SAC - VandenBos
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
Dollarhide

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
Stability Trend: 

Bottom Line

As expected, snowpack much thicker near Dollarhide than in eastern portion of this zone. Weak layer of concern is 4-5cm thick layer of 2-2.5mm facets, which was variably reactive in stability tests.

Media

(4/5/2020) E/NE facing slope at 8,400' near Dollarhide Summit. Crown is visible beneath cornice. Obviously wind-loaded slope, but based on width of crown it may have failed on some sort of persistent weak layer.
(4/5/2020) SE facing slope at 9,100', just SW of Dollarhide Summit. Crown spans the width of the pictured slope, estimated 1-2' deep. Failed in heavily wind-loaded terrain, likely sometime during last week's storm. Suspect presence of persistent weak layer based on width of crown.
(4/5/2020) Top of the slide that produced wet debris above Warm Springs road near Frenchmans Bend. Upper portion of slope faces NNE at 7,800'. This is one of the paths that buried the road last year.

Advanced Information

Weather Summary

Afternoon weather obs: Mostly cloudy skies increasing to overcast and then obscured. Precipitation picked up around 1645, with a bout of S2-S3 snowfall lasting until exit from the field at 1800. Rain/snow line was hovering around 5,800-6,000'.

Snowpack Observations

Upper snowpack was surprisingly wet, it felt like it had been rained on a bit or undergone some intense ambient melting. Liquid water had penetrated about 30-40cm down into the snowpack, slowed by several crusts. New/old interface was very wet, borderline slush, down 25cm. Lower down, this interface was closer to 15cm down, thanks to amount of melt. Weak layer of concern was down 45 cm, a layer of 2-2.5mm FC below a 2cm MFcr. These FC were ever so slightly moist where I dug, at 8,000' on a NE-facing slope, and produced variably snowpack test results. ECTs produced ECTNs in the upper single digits to low teens on both the new/old interface and the facets down 45cm. CPST produced consistent failures to end in the upper 20s/100 to low 30s/100.

(4/5/2020) Snowpack in the Dollarhide Summit area. A prominent band of facets below a crust produced unstable snowpack test results here. This layer is about 1.5 feet deep.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: Down 45cm
Location rose filled in for where problem was observed

Terrain Use

Avoided traveling in avalanche terrain due to uncertainty around persistent slab problem.

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