Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You can trigger large avalanches in wind-drifted areas at mid and upper elevations. You may be able to trigger avalanches that could break widely across terrain features in the eastern mountains and foothills. Prepare for very cold temperatures and deep snow hazards.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Use extra caution on leeward slopes steeper than 35 degrees. Watch for plumes of blowing snow as an indicator of where fresh slabs are forming. You can avoid triggering these avalanches by sticking to lower elevation, wind-sheltered terrain or scoured, windward slopes. 

    Expect east winds just strong enough to transport snow and form fresh slabs at upper elevations. Earlier in the week, southwest winds formed more widespread slabs at upper elevations. You may be able to trigger avalanches big enough to kill you at upper elevations. Any avalanches below treeline will likely be small loose slides. If you're traveling in the mountains well east of the Cascade crest, see below.

    (12/13/2022)

    An example of signs that you could trigger an avalanche, cracks shoot through fresh wind slabs. Hinkhouse pk, NE, above treeline

    Photo: Will Govus

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Near and east of Mazama consider the potential for triggering dangerous and surprising avalanches. With the recent snow, keep an eye out for signs of instability. If you see cracks shooting through the snow, experience loud collapses, or find strong over weak layers that produce sudden or propagating test results, stick to lower-angled slopes. You'll find a weak layer of facets in the lower half to a third of the snowpack and often under one or two crusts. 

    Triggering an avalanche on older weak layers near Washington Pass and the Cascade crest is unlikely but not out of the question. A few observations during past loading events indicate persistent slab avalanches could be possible near valley bottoms and in isolated areas above 7,000ft, where the mid-November facets are still weak. If you hit the wrong spot, you could trigger a dangerous avalanche.  

    (12/18/2022)

    Very small persistent slab avalanches released on unsupported features when a skier approached from above.  Silverstar - Below Treeline

    Photo: Katie Warren

Avalanche Discussion

Observers continue to report lots of collapsing and cracks shooting through the snow in the eastern foothills. On Tuesday, observers near Washington Pass reported triggering small loose avalanches in the new snow in steep terrain. The mountains close to the Cascade crest picked up 0.8" of water equivalent and close to 20" of snow through Tuedsay.

Temperatures are extremely cold and have been keeping the snow very light and dry. Bring plenty of warm layers and monitor exposed skin for cold injuries. With all the new snow, falling in tree wells and holes around creeks and boulders can be dangerous. Keep your partners in sight and within earshot.

The December 18th interface holds weak grains of small facets, surface hoar, and crusts on southerly aspects. Additionally, you can find another interface from December 8th about 2 feet below the snow surface.

Regions covered