Pro Field Report
Basic Information
Observation Details
Observation Date:
December 23, 2019Submitted:
December 23, 2019Observer:
SAC - Martin Stefan (off duty)Zone or Region:
Banner SummitLocation:
Cape Horn NE armSigns of Unstable Snow
Recent Avalanches?
None ObservedCracking?
None ExperiencedCollapsing?
Isolated
Collapsing on wind-stiffened snow at ridgetop
Snow Stability
Stability Rating:
FairConfidence in Rating:
ModerateStability Trend:
SteadyBottom Line
Plenty of collapsing indicates that there are still active weak layers in the snowpack.
Advanced Information
Weather Summary
Cloud Cover:
OvercastTemperature:
30s at highway, mid 20s est at elevationWind:
Light , SHigh 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. |
|
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
|
|
Comments: Sensitivity varies between stubborn and reactive |
Terrain Use
I avoided avalanche terrain