Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

Fresh slabs of wind drifted snow are the primary danger at mid and upper elevations. Utilize a lower angled line to reduce the likelihood of triggering an avalanche in wind loaded terrain. Use extra caution in rolling terrain or during poor visibility to mitigate the danger from early season-like hazards. 

Avalanche problems

  • Wind Slabs

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

    Deep, thick wind slabs were found  pretty much everywhere but were unreactive on a short, steep slopes at treeline. You might still trigger one in unsupported terrain on Tuesday. Since signs of wind transported snow are also pretty much everywhere, track the snow depth over the rain crust below to hunt down areas holding deeper slabs.  Strong winds may have created a more haphazard loading pattern than normal

    Slope tests didn't show much on Monday as the slabs were just too thick and "sticky." Hand pits did show where you could get a more planar shear and therefore where the likelihood of triggering a slab was higher. The best bet will be to just steer around steep, convex, wind loaded features where the slabs have the least amount of support from below. 

     

    Scoured or eroded snow surfaces are a telltale sign the wind has been at work stripping the snow from upwind slopes and depositing it into slabs on the other side of a ridge.

    Photo: Julz Holder

Avalanche Discussion

Non-avalanche hazards include dense, grabby new snow, patches of exposed crust, frozen avalanche debris, exposed creeks, and other natural hazards exposed by recent rain. Multiple observers out on Monday noted they felt the greatest hazard was not avalanche-related, but dealing with any or all of the above in poor visibility.

West Central weather stations recorded 0.6-0.9” of snow water equivalent from the last storm while White Chuck picked up 5” of new snow. Observations across the west slopes pointed towards a few different problems. Wet avalanche activity was the headline in Snoqualmie Pass with sun breaks warming the surface and triggering a round of small wet loose avalanches. One small natural slab avalanche was reported as well. Stevens Pass observers found similar but less widespread activity due to less sun and new snow. In West North (which received similar precipitation and snowfall as West Central) thick but mostly unreactive wind slabs were found down to and sometimes below treeline.

Keep an eye out for and reduce exposure to glide cracks and hanging slabs in steep rocky terrain above. The sun is not forecast to make an appearance, but if it does look for the usual signs of instability like wet, unsupportable snow surfaces, rollerballs, or small avalanches. Stay off and away from steep slopes if you to observe any of the above in your travels

If you’re out and about, please send us some pictures of what you’re seeing by submitting an observation.

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