Professional Observation
Basic Information
Observation Details
Observation Date:
December 18, 2020Submitted:
December 18, 2020Observer:
WAC - Killian SumpZone or Region:
Southern WallowasLocation:
Southern Wallowas - Norway BasinSigns of Unstable Snow
Recent Avalanches?
YesCracking?
IsolatedCollapsing?
WidespreadSnow Stability
Stability Rating:
PoorConfidence in Rating:
ModerateStability Trend:
ImprovingBottom Line
On the night of the 16th and morning of the 17th, the Southern Wallowas recieved over an inch of water and 30 cm, or 1 foot of new snow at 7,000 ft. Today, on Friday the 18th, I observed shooting cracks, whumphing, and two recent avalanches. Visibility was quite limited, otherwise I may have seen more. Those two avalanches slid at 7,200 ft on North aspects (NE and NW), about a foot and a half down (40-50 cm), on a weak layer of faceted snow mixed with buried surface hoar. This weak layer was also observed buried on an ENE aspect at 7,200 ft near treeline a few days prior.
Media
Advanced Information
Weather Summary
Cloud Cover:
ObscuredTemperature:
23Wind:
Light , SWLight snow, fog.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Past 24 hours |
Norway Basin NW 7,200 |
D1.5 | SS | O-Old Snow | 40 cm |
N-Natural u-Unintentional |
None | |
| 2 | Past 24 hours |
Norway Basin NE 7,250 |
D1.5 | SS | O-Old Snow | 50 cm |
N-Natural u-Unintentional |
None | |
|
|
None |
Observed 50 cm crowns visible on 1 NW and 1 NE slope. Slabs ran on a layer of buried surface hoar and facets. Bed surface was 39 degrees and each avalanche track was about 50 feet wide. Appears to have been triggered during storm.
Snowpack Observations
On Tuesday, we found buried surface hoar on an ENE aspect at 7,200 ft. There was not enough snow on top of it to cause avalanches, but we did receive a touchy result of CT5 (Resistant Planar) on our compression test. This poor structure was tested on Wednesday night when 30 cm of new snow and an inch of water was added to the equation. I did not perform a test today but did observe multiple natural avalanches.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Storm Slab
|
|
Layer Depth/Date: 40-50cm |
|||
Persistent Slab
|
|
Layer Depth/Date: 40-50 cm |
|||
| None Specified |
|
Terrain Use
Just out for a skin in low angle terrain
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