Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Winter’s back! Snow and wind will buffet the West North zone with increasing forces on Friday, and avalanche danger will rise as the storm continues. When you see active wind transport loading snow on a slope, or find firm or textured pillows of snow, consider avoiding these areas on slopes steeper than 35 degrees. Search out non wind-loaded areas or lower angle slopes to recreate on. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    It is possible that you could trigger an avalanche on an isolated wind slab on Friday. The slabs will continue to develop near and above treeline throughout the day.  As the snowfall continues, these deposits will increase in depth and size, amounting to a foot or more deep. Search for pillows on leeward slopes, around the base of cliffs, and along the sides of gullies or features. Use small test slopes or wind lips to determine how the snow is behaving. If you see long shooting cracks or create a tiny avalanche on one of these small features then avoid going onto larger steep slopes with similar snow characteristics.

    (12/9/2021)

    An example of a skier triggered wind slab avalanche which occurred at Mt Hood on Thursday.

    Photo: Andrew Kiefer

Avalanche Discussion

In steep areas without wind loading, you may trigger small loose dry avalanches (sluffs) in the top few inches of snow.  Be aware of this as you're traveling down a slope or if someone is below you.  As for the rest of the snowpack,  above approximately 4000ft there is a base from early season snowfalls that was subsequently rained on, forming a stout late November crust. In the last week, we’ve received over a foot of snow, and more than two feet of additional snow will accumulate by the end of the weekend. Currently, avalanches will remain limited to layers sitting on top of the late November crust. 

As the season is just beginning, our snowpack information is limited. There is also a lot of uncertainty in the reactivity of these slabs as the snow mounts. Help us write better forecasts by submitting an observation when you get back from a day out. And since it’s early season, keep an eye out for hazards such as exposed creeks and shallowly buried rocks and trees while you’re traveling.

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