Professional Observation
Basic Information
Observation Details
Observation Date:
February 7, 2021 - February 11, 2021Submitted:
February 11, 2021Observer:
WAC - Killian Sump, Towner MenefeeZone or Region:
Southern WallowasLocation:
Norway Basin, South Fork ImnahaSigns of Unstable Snow
Recent Avalanches?
YesCracking?
None ExperiencedCollapsing?
None ExperiencedSnow Stability
Stability Rating:
GoodConfidence in Rating:
ModerateStability Trend:
SteadyBottom Line
Spent five days in Norway Basin and to the north into the South Fork of the Imnaha during a period of cold and clear skies. Winds were light and variable near treeline but moderate-strong in the alpine, as plumes of wind blown snow were seen at ridgelines. Most N facing alpine terrain was wind scoured. South and West aspects developed a solar crust. We even observed some small wet loose slides on Tuesday, as well as some small pockets of wind slab release in the alpine. After digging multiple pits below treeline on N and E aspects, we found it difficult to find a distinguishable rain crust from Jan 12/13. That layer appears to be more of a density change now, keeping in mind 75 cm (2.5 feet) of snow linger on top of this old layer.
Advanced Information
Weather Summary
Cloud Cover:
ClearTemperature:
10 - 23 degrees FWind:
LightCold temperatures and clear skies dominated the Wallowas these last few days, with winds light and variable near treeline, and moderate to strong in the alpine. Winds came primarily from the NW and W. Sun exposure formed crusts on south and west facing slopes, and calm clear nights allowed for some near surface faceting on colder aspects. New snow has come today, as a mellow front from the north moved in and light snow has been falling since this morning.
Avalanche Observations
Small wet loose on alpine south facing terrain, starting in rocks. Small wind pockets seen naturally releasing.
Snowpack Observations
We dug snow pits on N and E aspects at 6,500 and 6,800 ft, respectively. With a height of snow between 260 cm and 195 cm, we found the old Jan 12/13 snow down around 75 cm or 2.5 ft. This being our layer of concern, we found no propagation in our Extended Column Tests. It appears, where we were, that this old snow/old snow interface is bonding well.
Avalanche Problems
| Problem | Location | Distribution | Sensitivity | Size | Comments |
|---|---|---|---|---|---|
Dry Loose
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Wind Slab
|
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| None Specified |
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Terrain Use
We chose to ski primarily near and below treeline, on N and E aspects where soft snow could be found. We had a 'Status Quo' mindset most of the time.
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