Pro Field Report

Basic Information

Observation Details

Observation Date:
January 6, 2021
Submitted:
January 6, 2021
Observer:
SAC - Davis, Creelman
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
Peak 2 (Primarily SW-S-E-NE, Middle and Upper Elevations)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Snow Stability

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

Bottom Line

Slab avalanches during our recent storm released as shallow wind slabs as well as deeper persistent slabs that failed on a weak facet layer buried in mid-December.

Although we did not experience collapsing or cracking, the overall snowpack structure and snowpack test scores were concerning. This setup will be slow to heal.

Media/Attachments

A collection of avalanches including shallower wind slabs and deeper persistent slabs on the E-face of Peak 2 in the Soldier Mountains. Crowns spanned the entire bowl. Some sections of the crown are highlighted with red arrows. E to SE facing slopes at 9,200'.
Smaller wind slabs from above the rocks stepped down in a number of locations within and below the main rock band.
Much of the crown on lookers right had been filled in by continued N wind.
A deeper portion of the crown on lookers right.
A deeper portion of the crown on lookers right.
Image of a snow profile on Peak 2 in the Soldier Mountains. The weak layer of facets in the lower third of the snowpack showed propagating results. This was the primary failure layer of the nearby avalanche.
This persistent slab avalanche failed on a ENE-facing slope at around 9,200' in the Soldier Mountains.
There were a half dozen of these small slabs that failed at low elevation in the foothills between Soldier and Fairfield. The majority were on cross-loaded E aspects.
https://www.youtube.com/watch?v=3NI1FAE62t8&t=9s

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
25 F
Wind:
Light , SW
New/Recent Snowfall:
HST = 20 cm

Mild and calm. Clouds increased from the W around 3 PM.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Jan 5, 2021
(+/- 1 day) 		Soldier Mountain Crest
E 9200ft 		D2 U-Unknown
This persistent slab avalanche failed on a ENE-facing slope at around 9,200' in the Soldier Mountains.
Report
2 Jan 4, 2021
(+/- 1 day) 		Peak 2 Soldier Mtns - Big Bowl and Big Bowl Chutes
E 9200ft 		D2 HS-Hard Slab N-Natural
A collection of avalanches including shallower wind slabs and deeper persistent slabs on the E-face of Peak 2 in the Soldier Mountains. Crowns spanned the entire bowl. Some sections of the crown are highlighted with red arrows. E to SE facing slopes at 9,200'.
Smaller wind slabs from above the rocks stepped down in a number of locations within and below the main rock band.
A deeper portion of the crown on lookers right.
A deeper portion of the crown on lookers right.
Much of the crown on lookers right had been filled in by continued N wind.
Report
Soldier Mountain Crest
Peak 2 Soldier Mtns - Big Bowl and Big Bowl Chutes

Snowpack Observations

The December facet layer was obvious with pole pokes as we traveled. In this location, a stronger 20-30 cm 4F slab sat just above it.

Image of a snow profile on Peak 2 in the Soldier Mountains. The weak layer of facets in the lower third of the snowpack showed propagating results. This was the primary failure layer of the nearby avalanche.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
None Specified
Isolated
Specific
Widespread
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 40-60 cm
Weak Layer(s): Dec 11, 2020 (FCsf)

Terrain Use

We planned to avoid slopes steeper than 33 degrees that could produce a D2 avalanche. We stuck to that plan.