Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
January 29, 2021
Submitted:
January 29, 2021
Observer:
SAC - Chris Lundy (off duty)
Zone or Region:
Banner Summit
Location:
Bull Trout (7000-8000, primarily E)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
Isolated
One large collapse around some buried logs

Snow Stability

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

Bottom Line

16" of recent storm snow is sitting atop weak old snow surfaces, including surface hoar. You could likely trigger a slide on slopes over about 38* degrees and on steep, convex rolls. The December facet layer is buried around 4' deep, but is showing little to no sign of strengthening.

Media/Attachments

https://youtu.be/bhRqZjsyATY

Advanced Information

Weather Summary

Cloud Cover:
Obscured
Temperature:
increasing
Wind:
Calm
New/Recent Snowfall:
40cm settled HST, 5-7cm HN from 1100-1600

S1 most of the day, with periods of S2. Increasing temps led to soggy conditions at lower elevations (at least clothing-wise, snow stayed dry).

Avalanche Observations

Terrible visibility

Snowpack Observations

HS around 160-170cm in the terrain we traveled through, with the top 40cm since 1/26.

@7300, E: This was below rain line. FC above and below rain crust, but ECTX in top 60cm of snowpack.

@8000, E: HS 165cm. SH and FCsf found beneath 40cm HST. ECTP11. 12/11 FC 130cm down - still 4F and showing little signs of change. See photo and video.

Unsure of distribution of SH but it was found in several hand pits at mid elevations. Does not seem to be enough load on it for now, although I suspect you could have triggered a small slide on something over 38*.

Snowpit on E facing slope at 8000'. Buried surface hoar down 16" produced poor snowpack test scores. The December facet layer is buried more than 4' deep.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Storm Slab
Unknown
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
Layer Depth/Date: 40cm - 1/26 interface
Comments: ECTP11 where 1/26 = SH. Rose indicates observed terrain.
Deep 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: 120-130cm
Weak Layer(s): Nov 7, 2020 (DH)
Comments: Rose indicates observed terrain. Sensitivity based purely on depth.

We did not get into wind-exposed, upper elevation terrain.

Terrain Use

We traveled on small slopes around 30 degrees but otherwise avoided avalanche terrain.