Pro Field Report

Basic Information

Observation Details

Observation Date:
January 11, 2021
Submitted:
January 12, 2021
Observer:
SAC - VandenBos
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Butterfield (6,700-9,700', mostly E-NE-N-NW)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Widespread
Collapsing? 
Widespread

Snow Stability

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

Bottom Line

Snowpack in this area is teetering on the edge, won't take much to push it past the brink. Expect avalanches to be triggered with light loads and the likelihood of natural avalanches to increase rapidly with loading.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Wind:
Calm

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Jan 10, 2021
(+/- 3 days) 		Lake Creek Headwall
SW 10000ft 		D3 SS-Soft Slab N-Natural
Very large persistent slab avalanche on the headwall at the back of Lake Creek. Crown is at least 1000' wide. Based on earlier observations it likely failed between 1/10 and 1/11.
Report
1 Jan 10, 2021
(+/- 3 days) 		Lake Creek
NW 9000ft 		D2 SS-Soft Slab AW-Wildlife
Elk (?) triggered avalanche above the Lake Creek drainage.
Report
Lake Creek Headwall
Lake Creek

Observed some D1.5 piles in steep, rocky, solar terrain of the Boulders. Most of these looked like point releases but one had a slabbier character to it.

Snowpack Observations

Surfaces are very weak on the northern half of the compass in this zone. Upper 3-5cm has undergone some intense faceting, particularly below level of the inversion. Additionally, widespread 3-6mm SH is present up to the top of Butterfield. Sun today helped knock down some of this on steeper solars but calm winds weren't doing us any favors there. In conjunction with observations further south in the WRV (as far south as Hailey/Indian Creek) I suspect this is could potentially be a widespread problem as it gets buried Tuesday and Wednesday. At this point it doesn't look like we will be putting a huge load on it, but smaller slabs could end up being triggers for December facets.

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: down 45-50cm
Weak Layer(s): Dec 11, 2020 (FCsf)
Comments: Could see these starting to approach D3, thanks to slab thickness/connectivity

Terrain Use

Continuing to avoid avalanche terrain steeper than 30 and terrain threatened by hazard from above.