Pro Field Report

Basic Information

Observation Details

Observation Date:
December 18, 2021
Submitted:
December 18, 2021
Observer:
SAC - VandenBos
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Baker Creek (6,700-9,500', most aspects)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
Isolated
Isolated cracking in recently deposited wind slabs along upper elevation ridgelines. I experienced two collapses, one muffled collapse on a wind drifted ridge, and a deep, rumbling collapse on a slope that held old snow underneath the new snow.

Snow Stability

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

Bottom Line

The likelihood of impacting the weak layer is very gradually decreasing, thanks to the stiffness of the slab above it, but this layer of weak snow is showing little signs of healing.

Media/Attachments

These are the facets that have produced many avalanches are and continuing to produce collapses and unstable snowpack test scores. The crystals aren't huge, 2-4mm, but are cupped, striated, and chained where they are at their worst.
Radiation recrystallization crust found on a 37 degree SSE-facing slope at 7,500'. The upper 1/3 of the snow in the image are dry PP that are/have rapidly faceted under very strong gradients. The grey stripe is a thin icy lens and the grains below are well-aerated melt-freeze polycrystals
Small, somewhat older wind slab (small starting zone has been refilled with a secondary drift). Observed in the Baker Creek drainage on a SE aspect at 9,500'.
Persistent slab avalanches that failed in the Baker Creek drainage, likely near the tail end of the big storm (probably 12/14). Nearly a dozen similar slides were observed. Northeast aspect at 8,200'.
Persistent slab avalanche in a wind loaded location, observed in the Baker Creek drainage on a north aspect at 9,000'.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Calm , NW

Calm until the late afternoon, then winds picking up out of the W/NW. Overcast skies throughout the afternoon. No precip.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
3 Dec 14, 2021
(+/- 1 day) 		Baker Creek
NE 9500ft 		D2 N-Natural Report
10 Dec 14, 2021
(+/- 1 day) 		Baker Creek
NE 9000ft 		D1.5 N-Natural Report
Baker Creek
Baker Creek

Snowpack Observations

Dug at 9,000' on N aspect where HS=125-130cm. The slab here is 80-85cm thick, F- at the top grading to 1F at the base. Below this I found a few iterations of subtle crusts and ugly facets, the worst of which are ~10cm below the base of the slab. Here, grains are up to 4mm in size and are cupped and striated. This layer produced ECTP 15 and 21 and CPST 18/100 END. The slab of new snow has settled and gained enough strength to keep you off the ground and above the weak layer, even on the sled. Because of this, likelihood of triggering is very gradually decreasing. However, my unstable snowpack test scores, the collapses I experienced, and the appearance of these grains indicate that this layer is healing quite slowly.

On solar aspects at middle and lower elevations, the weak snow described above does not exist. Here, the entire snowpack (HS=65-70cm) was deposited in the past week. It is hard to imagine an avalanche occurring in a snowpack that looks like this in the absence of wind loading.

A note about surfaces: I observed very similar radiation recrystallization crusts in the Baker drainage as those I observed the previous afternoon in the Durance area. The distribution was similar: SSE-WSW on slopes that were steeper than ~32 degrees. If this ends up being a player (seems fairly likely, at least in the short term, if we throw a quick 1" of SWE on it) the very specific distribution will be tricky to deal with. Due to the very low sun angle right now, this crust doesn't exist until the slope steepens into/above the low 30s... prime-time avalanche terrain.

Snowpit dug at 9,000' on a north aspect above the Baker Creek drainage. Pictured is the slab after performing an ECT, which produced an ECTP 15.

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
 Weak Layer(s): Dec 11, 2021 (FC)
Comments: Shaded based on where problem is known to exist.