Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
March 18, 2022
Submitted:
March 18, 2022
Observer:
Chris Lundy
Zone or Region:
Banner Summit
Location:
Cape Horn Ridge (6700-8800', SE-E-NE)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Snow Stability

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

Bottom Line

The persistent slab problem seems less pronounced than what I observed in the northern Sawtooths yesterday, primarily due to a thinner slab from less snowfall since March 8th. I found the weak layer (facets on a crust, or just facets) on shady, mid to upper elevation slopes. It was buried beneath a 14" thick slab that produced poor test results.

Media/Attachments

https://drive.google.com/file/d/1VIyaBJpsOhYPv-_bwEVt6BSEse2_dutX/view?usp=sharing

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Wind:
Light , SW
New/Recent Snowfall:
Trace of new overnight

Morning was close to overcast, but transitioned to broken by afternoon with a mix of sun and clouds. Temps were warm, but the clouds and breeze kept things cooler than it felt yesterday. Winds were light but gusty, there were brief spells when it was blowing moderate and moving small amounts of snow.

Snowpack Observations

Main objective was looking at weak layers in the top portion of the snowpack, particularly the 3/8 crust/facet layer.

@7800', E-NE: 25cm of snow on 3/8 - no real slab

@8200', NE: 3/8 rain crust 33cm down. ECTN's or ECTX's, but clean hand shears.

@8400', NE: No rain crust, but obvious, well-developed 2cm thick FC layer down 35cm at the 3/8 interface. ECTP13, ECTN (x3). 1/20 down 50cm, F+ FC, ECTX. This was a "shady" NE in some trees, compared to the sunnier NE in the next pit.

@8800', NE: HS 240cm. 3/8 MFcr/FC down 35cm. I'm fairly certain this crust formed during the warm spell after the rain event - it didn't rain this high in the Banner zone. Bottom of slab was 4F+. ECTP8,13,15 (see video). 1/20 down about 55cm, F+ FC, ECTX.

TL;DR: Persistent slab problem seems more pronounced where a crust exists at the 3/8 interface. Seems there is just barely enough of a slab.

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: 35cm
Weak Layer(s): Mar 8, 2022 (FC)
Comments: Rose is forecasted location
Wet Loose
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 10-20cm
Comments: I did not gather much info on this problem, but pushing on one small mid elevation slope, the snow seemed like it wanted to peel off the 3/8 crust

Terrain Use

I avoided slopes 35* and over