Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
April 2, 2023
Submitted:
April 3, 2023
Observer:
SAC - VandenBos (off duty), O'Connor
Zone or Region:
Banner Summit
Location:
Bear Creek (6,500-8,500', all aspects)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
Isolated
Avalanches observed refers to large remotely triggered avalanche described below.

Media/Attachments

https://youtu.be/POjHXM2nX80

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Wind:
Moderate , W
New/Recent Snowfall:
40cm from April Fool's storm

Classic spring weather. Periods of warm, bright sun, then squalls producing S3 snowfall and moderate to strong winds with very minimal visibility. I love those days.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Apr 2, 2023 4:31 pm
(Exact)
Bear Creek
NE 8000ft
D2.5 SS-Soft Slab O-Old Snow 2ft AS-Skier
r-Remote
This large avalanche was remotely triggered by skiers on the low angle ridge above in the Banner Summit area. It failed 2+ feet deep, 1,000' wide, and ran downslope nearly 1,000' to the end of its historic runout, putting debris in the creek bottom below. It failed on a NE-facing slope at 8,000' on a 2-3cm thick melt-freeze crusts with facets on top.
Report
Link
Bear Creek

Aside from the one we triggered, we did not see any other large, persistent slab avalanches. We saw evidence of a decent amount of mid-storm activity, though much of this was masked by continuing snowfall and wind. Enough snow had been moving around that evidence of large slides may have been masked as well. There were periods of good visibility when we would have seen slides in the nearby terrain, and periods of very poor visibility where we could hardly see our skis.

Snowpack Observations

Brief periods of sun were quickly affecting the new snow on solars. The upper 15cm of the snowpack quickly transformed, feeling much denser, moister, and heavier. Once it cooled and refroze there was a 3-4cm thick aerated MFcr just below the snow surface. This was occurring on flat slopes and even low angle northerly slopes (high sun angle in April), but slightly steeper norths remained cold and dry, providing some excellent skiing.

Avalanche Problems

We did not encounter a distinct wind slab problem, just areas where wind loading had added to the persistent slab problem.

Terrain Use

We traveled cautiously. We had no intention of entering large, consequential avalanche terrain, and we stuck to that plan. The skiing and riding were very good, it would have been easy to deviate from that plan.