Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
February 27, 2021
Submitted:
February 27, 2021
Observer:
Chris Lundy
Zone or Region:
Galena Summit and Eastern Mtns
Location:
4th of July Lake (9000-9700', NW-W-SW)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced
Avalanches refer to slides glassed in the northern Sawtooths

Snow Stability

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

Bottom Line

Weak layers buried in the top 2-3' of the snowpack seem most prevalent on solar aspects. While I did not experience signs of instability, the buried weak layers combined with recent new snow and wind lead to me believe the dangerous conditions exist - primarily in wind-loaded, upper elevation terrain.

Media/Attachments

https://youtu.be/U3VhD6lbT0I

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Temperature:
teens F (estimated)
Wind:
Light , NW
New/Recent Snowfall:
20-25cm HST since 2/25

Skies were initially SCT to BKN, but squally weather in the afternoon lead to periods of OVC and a trace of new snow fell. I did not get onto any exposed ridgelines, but winds up high seem to be blowing light to moderate and were occasionally moving snow. Ski pen averaged around 20-25cm.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
7 Feb 26, 2021
(+/- 1 day)
Northern Sawtooths
NE ft
D1.5 N-Natural
Natural avalanches in the northern Sawtooths. Several of these likely released due to loading from sprindrift trickling down cliffy terrain above. Five crowns are visible, but several are partially filled in.
Report
Northern Sawtooths

I had glassed the Sawtooths from Imogene to Goat Creek, and saw over a half-dozen slabs. Almost all released in the aprons below cliffs. I had reasonable light in the 4th of July drainage and did not see any avalanche activity.

Snowpack Observations

@9460', NW: HS 185cm. ECTX x2 in the top 130cm of the snowpack. No obvious weak layer observed. 12/11 down about 130cm.

@9500', SW, 30*: HS 165cm. Three prominent PWLs observed ranging from 60-90cm down. The uppermost consisted of a thin layer of FC and produced one ECTP30+++ and one ECTX. The other two had very soft/thin crusts associated with them - much less pronounced than I've seen elsewhere - these were ECTX x2. See photo.

There were enough clouds and cold temps that solars remained cold and dry.

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: 60-90cm
Comments: Rose indicates where I observed the problem. I also dug on a shady aspect, but did not see any prominent weak layers.

I did not get into the alpine, but based on the drifting I observed at treeline and what I could see up high, I'm fairly certain there was a wind slab problem at upper elevations.

Terrain Use

I avoided avalanche terrain.