Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Thu
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Evening Update: You could trigger slab avalanches near ridgetops where winds have drifted fresh slabs and at lower elevations in the eastern mountains and foothills of the Methow Valley. Warming temperatures and sun may contribute to avalanche danger at lower elevations. Snow and avalanche conditions vary widely with relatively deep snowpack near Washington Pass and the Cascade crest and shallow but consistent coverage in the eastern mountains. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    You may be able to trigger shallow avalanches on the leeward sides of some high ridges. Pay attention to localized wind loading direction as it may be subtle. Steer around areas of fresh pillows of snow or stick to lower-angled slopes. Avoid areas with terrain traps like rocks and cliffs where find fresh wind slabs could have dangerous consequences.

    While it's now difficult to trigger bigger avalanches, they could be dangerous if you hit the wrong spot.  If you see cracks shooting through the snow, experience loud collapses at upper elevations, or find obvious strong over weak layers in the snowpack, stick to slopes under 35 degrees or windward slopes. 

    (12/13/2022)

    Cracks shoot through fresh wind slabs. Hinkhouse Peak. NE, above treeline

    Photo: Will Govus

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Expect more dangerous avalanche conditions in the mountains east of Mazama and the low hills of the Methow Valley. Warming temperatures and a very weak snowpack could create heightened avalanche conditions in the eastern mountains. For weeks, observers have reported loud collapsing and cracks that propagate long distances in valley bottoms and areas of shallow snowpack well east of the Cascade crest. If you experience these warning signs, stay far away from and out from under slopes 35 degrees and steeper. Be suspect of steep sun-exposed east, south, and west aspects.

    On Wednesday, an observer reported a large natural slab avalanche, about 500 feet wide, in Finley Canyon on the far eastern edge of the zone. You can find a weak layer of the mid-November facets in the lower half to third of the snowpack and often under one or two crusts. On Sunday, an observer on Delancey Ridge reported propagating test results on the facets, 50cm below the surface. you can find many other reports of cracking and collapsing in the observation database.

    (12/14/2022) Large avalanche crown running across the top of an east facing slope in Finley Canyon. Photo: Public Obs

Avalanche Discussion

On Tuesday, observers on Hinkhouse peak reported cracking in freshly drifted wind slabs on the northeast aspect, just below the ridge. The northwest aspects were free of wind slabs. On Monday, observer, Drew Lovell, reported on conditions both north and south of Washington Pass. You may be able to find a layer of large surface hoar about a foot below the snow surface. The layer was buried on December 8th on a variety of slopes but has generally not been a problem for avalanches in this zone.

Over the weekend, a storm brought about a foot of snow to the top of Washington Pass. Observers reported a number of small loose dry avalanches in steep terrain. A small number of slab avalanches were reported from aprons below cliffs or immediate leeward sides of ridges. On Saturday, observers reported two notably deep avalanches on Big Kangaroo Peak, WNW, 7,700ft. While we can't confirm this, there's suspicion that they may have run on older weak layers. On December 3rd, I experienced a large collapse on an adjacent slope in a shallow area (~100cm) of older drifted slabs resting on the mid-November facets. These outliers in the Kangaroo Ridge are contrary to most other observations from mid to upper elevations near the Cascade crest that report the layer as unreactive or less concerning. 

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