Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

On Thursday, you can trigger a wind slab avalanche above treeline, just below ridge tops. Watch for signs of blowing snow and stay off of steeper, leeward slopes where the wind deposits fresh slabs. Expect a weak snowpack in the eastern mountains where you may see signs of instability like whumphing collapse and cracks shooting through the snow. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    You may see plumes of blowing snow as an indicator of these avalanches. Pay attention to localized wind drifting direction to clue you into where you may be able to trigger an avalanche. To stay safe, steer around fresh pillows of snow or stick to windward terrain and slopes less than 35 degrees. Avoid areas with terrain traps like rocks and cliffs where avalanches could have dangerous consequences.

    For Thursday, expect more wind out of the northeast. While it's now difficult to trigger deeper 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 lower-angled slopes. 

    (12/14/2022)

    Blowing snow from northeast winds in the Blue Lake area.

    Photo: Willie Webster

Avalanche Discussion

We've received decent confirmation of the newly developed wind slabs. On Wednesday, an observer reported plumes of blowing snow from northeast wind in the Blue Lake area. On Tuesday, observers on the northeast aspect of Hinkhouse peak reported cracking in freshly drifted wind slabs above treeline.

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, buried December 8th, about a foot below the snow surface. The layer has generally not been a problem for avalanches in this zone.

Over the weekend, a storm brought about a foot of snow and mostly small, soft avalanches. 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. While notable, these observations are outliers to most other observations from mid to upper elevations near the Cascade crest that report the layer as unreactive or less concerning. 

Further east,  the signs of instability are more consistent. Observers have reported collapsing in most valley bottoms and areas of shallow snowpack well east of the Cascade crest. You can find a weak layer of facets in the lower half to third of the snowpack and often under one or two crusts. On Wednesday, an observer in the hills of the central Methow Valley reported cracks that propagated 45 feet. On Sunday, an observer on Delancey Ridge reported propagating test results on the mid-November facets, 50cm below the surface. Interestingly, there have been few to no reports of related avalanches in these areas. 

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