Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
December 23, 2019
Submitted:
December 23, 2019
Observer:
SAC - Martin Stefan (off duty)
Zone or Region:
Banner Summit
Location:
Cape Horn NE arm

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
Isolated
Collapsing on wind-stiffened snow at ridgetop

Snow Stability

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

Bottom Line

Plenty of collapsing indicates that there are still active weak layers in the snowpack.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Temperature:
30s at highway, mid 20s est at elevation
Wind:
Light , S

High temperatures made the snow noticeably heavy below approx 7200ft even though the sun was behind clouds.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
3 NE ridge of Cape Horn
N 8400
D1 SS O-Old Snow 30cm N-Natural Partially drifted in old slide on N face of ridge at 8400ft, I assume it went on 12/7, possibly when wind shifted to S 12/17, but there is no way to be certain. Trigger is also assumed. There were slides of the same size in all similar terrain features along the ridge from 8400ft.
Avalanche at 8400ft on NE ridge of Cape Horn , Banner Summit area.

Snowpack Observations

There were plenty of collapses on the wind stiffened snow on top of the ridge. None of the collapses set off anything on the N side, and even though it looked wind loaded I could not get any cracks in the few wind pillows I could safely access.

Dug a pit on E facing 25deg terrain at 7800ft, 12/7 was there but was not responsive to my tests.

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
Comments: Sensitivity varies between stubborn and reactive

Terrain Use

I avoided avalanche terrain