Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
February 3, 2021
Submitted:
February 3, 2021
Observer:
SAC - Ethan Davis
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
Wells Summit

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
Widespread
I felt smaller 20-50' collapses under the recent storm snow. One loud collapse triggered by stepping off my skis into weak snow near the ground cracked slopes up to 200' away.

Snow Stability

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

Bottom Line

Weak snow interfaces under our recent storm snow (1/27) and near the ground (12/11) produced widespread collapsing and poor snowpack test scores. Given the setup, I was expecting to remotely trigger an avalanche in nearby steeper terrain.

I did not observe recent avalanche activity around Wells Summit, but I did observe a large, fresh slide in Croy Canyon near Hailey (see photo).

Media/Attachments

This large slide likely occurred sometime last night or early this morning (2/3). It's on 7,700' E-facing slope in Croy Canyon above Democrat Gulch.
ENE facing slope at 7,900'. Snow depth = 70 cm. ECTP3 and ECTP4 down 27 cm on (1/27) FCsf above a crust.
This near-surface facet layer sat above a crust and was responsible for poor snowpack test scores (ECTPs <5 taps) on ENE, NW and SW facing slopes around 8,000' on Wells Summit.
SW facing slope at 7,900'. Snow depth = 75 cm. ECTPV and ECTP1 down 27 cm on (1/27) FCsf above a crust.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Temperature:
20 F
Wind:
Light , NW
New/Recent Snowfall:
HST = 10 cm (4 in)

Very light snow flurries mid-day. Broken skies with clouds hanging in the Soldiers to the west, partly cloudy over the S. Smokys.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Feb 3, 2021
(+/- 1 day)
Croy Canyon - Bullion/Democrat Divide
E 7700ft
D2.5 N-Natural
This large slide likely occurred sometime last night or early this morning (2/3). It's on 7,700' E-facing slope in Croy Canyon above Democrat Gulch.
This large slide likely occurred sometime last night or early this morning (2/3). It's on 7,700' E-facing slope in Croy Canyon above Democrat Gulch.
Report
Croy Canyon - Bullion/Democrat Divide

I didn't see any recent avalanches around Wells Summit but last night's snow and wind certainly made these harder to detect. I had a good vantage point and visibility from Big Peak down to the southern tip of the Smokys around Buttercup.

Snowpack Observations

Overall height of snow was generally near 80 cm although thinner on steep S-SW-W facing slopes. Some of these low elevation sunnier slopes were free from snow or at least had a lot of sage poking through again.

I found a reactive 30 cm thick persistent slab problem (1/27) on all aspects at 8,000'. Slabs failed above crusts in a layer of near-surface facets; numerous ECTPs with 5 taps or fewer. I looked hard for surface hoar and couldn't find any.

The December facet layer near the ground was quiet in snowpack tests, although I'll admit I was paying more attention to the near-surface problem. It did not produce results in ECTs. However, the largest/loudest collapse I experienced was certainly within this layer.

ENE facing slope at 7,900'. Snow depth = 70 cm. ECTP3 and ECTP4 down 27 cm on (1/27) FCsf above a crust.
SW facing slope at 7,900'. Snow depth = 75 cm. ECTPV and ECTP1 down 27 cm on (1/27) FCsf above a crust.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 25 cm
Weak Layer(s): Jan 27, 2021 (FCsf)
Comments: ECT's failed on isolation or 5 hits and fewer. Aspects painted where observed.
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 50 cm
Weak Layer(s): Dec 11, 2020 (FCsf)
Comments: One loud, large collapse with boot pen on a south aspect. No notable results in snowpack tests. Aspects painted where observed.

Terrain Use

I avoided avalanche terrain.