Professional Observation
Basic Information
Observation Details
Observation Date:
February 26, 2021 - February 26, 2021Submitted:
February 26, 2021Observer:
WAC - Killian SumpZone or Region:
Southern WallowasLocation:
East Fork Pine Creek, Norway BasinSigns of Unstable Snow
Recent Avalanches?
YesCracking?
IsolatedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
PoorConfidence in Rating:
HighStability Trend:
WorseningBottom Line
Over Thursday night, the Southern Wallowas saw 1.5-2.5 ft of low density snow accumulation depending on elevation. This fell on top of 6-8 inches on light density powder, which is all sitting on top of a rain crust from Monday, Feb 22. I skied generally below 6,000 ft today, and observed no collapsing or shooting cracks, however a member in the party triggered a small, localized 12 in deep storm slab on a steep convexity/rollover in the trees. The new snow has not yet formed a consolidated slab, yet will still fail if it is steep enough. Winds were up today from the E thru NW on the north end of the compass, and I'd expect wind slab in places near and above treeline.
Advanced Information
Weather Summary
Cloud Cover:
Mostly CloudyTemperature:
20 degrees FWind:
Moderate , EAfter a rain event on Monday, we've had small pulses of light snow 3" at a time, adding to 9" along with strong gusty wind from the NW. Thursday night we received 20-30" of new, light snow depending on the elevation. Today Friday, the upper elevations saw strong winds from the E through NW, loading leeward terrain at ridgetops.
Avalanche Observations
| # | Date | Location | Size | Type | Bed Sfc | Depth | Trigger | Comments | Photo |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Past 24 hours |
N Headwall NW 7,150 |
D1.5 | SS | I-New/Old Interface | 2-3 ft | N-Natural | None | |
| 2 | Today |
East Fork Pine S 5800 |
D1 | SS | 1 ft |
AR-Snowboarder u-Unintentional |
cut steep rollover, no one injured | None | |
| 1 |
|
None |
The new snow, although light and not a cohesive slab yet, has not had enough time to bond to the old rain crust. The depth of these storm and wind slabs are going to change dramatically depending on where you are.
Snowpack Observations
In the Southern Wallowas, the 2/22 rain event was light, and is not a very stout crust in most places. During the rain event, we had no propagation during our ECT on a NW aspect near treeline, and the following cool down did good things for our overall pack stability, generally right side up structure. The image is from Monday 2/22 and currently has 2-3+ ft of new light snow on top. Watching the new snow settle over the coming days will be interesting, to see how the new load sets up, changes, and bonds to the old.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Storm Slab
|
|
Layer Depth/Date: 2-3+ ft |
|||
Wind Slab
|
|
Layer Depth/Date: 2.5-4 ft |
Terrain Use
Stayed below treeline today to avoid the wind and stayed in assessment mindset throughout the day, pushing it here and there on lower consequence steeper pitches.
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