Pro Field Report

Basic Information

Observation Details

Observation Date:
February 28, 2023
Submitted:
February 28, 2023
Observer:
SAC - Davis
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Headwaters near Savier Pk (7,400'-9,100')

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
Isolated
Cracking was associated with new snow in recent wind drifts as well as weak snow buried ~50 cm deep. Collapsing was on this weak snow (facets) on both NW and S facing, subtly wind affected slopes around 8,700'. Avalanches are listed below.

Snow Stability

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

Media/Attachments

This avalanche was likely triggered by a plow. Galena Summit, ESE @ 8,800'. The slide was approximately 8" deep and likely failed on a crust and facets beneath snowfall since Sunday (2/26).
Headwaters of the Salmon River, NW @ 8,700'. Weak snow layers exist near (2/26) and (2/18).
This slope produced a large collapse and repeated unstable snowpack test scores (ECTP5 x2). The failure layer presented as very weak 2 mm facets under a series of crusts. S @ 8,650'.
Active wind loading at middle and upper elevations in the Headwaters of the Salmon.
Natural loose snow avalanches triggered this small slab below a cliff band. Headwaters of the Salmon, NW @ 8,800'.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
Low Teens F
Wind:
Moderate , SW
New/Recent Snowfall:
HST since (2/26) = 10 cm at Headwaters TH, 30 cm at 9,100' near Saviers

It snowed most of the day. HN was hard to gauge but at least a few inches. Waves of snow and moderate wind caused ground blizzard conditions at middle and upper elevations and enough drifting to mostly cover my sled track in the valley bottom. There were occasional, brief breaks of blue midday but not long enough to affect the snow.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Galena Summit
E 8,800 		D1 SS I-New/Old Interface ~20 cm E/ESE. This path ran similarly on (2/21). Likely plow triggered.
This avalanche was likely triggered by a plow. Galena Summit, ESE @ 8,800'. The slide was approximately 8" deep and likely failed on a crust and facets beneath snowfall since Sunday (2/26).
1 Headwaters of the Salmon
NW 8,800 		D1.5 Natural loose snow avalanches triggered this small slab below a cliff band.
Natural loose snow avalanches triggered this small slab below a cliff band. Headwaters of the Salmon, NW @ 8,800'.

I had poor visibility, with only short windows to look at Bromaghin and the immediate surrounding slopes of the Headwaters. I only spotted one avalanche. However, I expect that natural avalanches released today based on the amount and intensity of wind loading in combination with weak layers at the new/old interface as well as deeper in the snowpack.

Snowpack Observations

The wind slab problem was obvious today. Lots of wind-loading going on at upper elevations. I expect that natural avalanches occurred today but a lot of the evidence will likely be obscured by continued loading. Wind slabs extended into middle elevations but I'd anticipate them to be smaller and less numerous.

We have the ingredients to have a persistent slab problem here. I experienced collapses in facets buried under 50 cm slabs. Wind affect at some point in the last 10 days likely helped tie some of these slabs together, but the collapses were not in obviously wind-loaded terrain.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 30-60
Comments: Most likely at upper elevations although I triggered one small, cross-loaded slope at middle elevations as well as several touchy cornices.
Persistent Slab
Isolated
Specific
Widespread
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 50 cm
Comments: I experienced large collapses on these aspects at around 8,800'. Digging in both spots revealed a weak layer of facets down about 50 cm. The facets on the S-facing slope were beneath a crust (ECTP5). I believe this is weak snow that formed in mid-Feb and was buried on or around (2/18).

Terrain Use

Solo travel, I avoided avalanche terrain.