Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

All the recent storm snow seems to be healing nicely. However, winds formed pockets of firmer slabs on exposed features even well below ridgelines. Steer around pillow-like slabs, especially on convex features and unsupported slopes.

Avalanche problems

  • Wind Slabs

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

    Moderate westerly winds on Thursday redistributed the new snow in some parts of the zone and built fresh slabs. As the winds shift southerly Thursday night, they could load additional aspects. If you start to notice slightly firmer snow, textured surfaces, drifts, or pillow-like slabs, then you’ve found the problem.

    Figuring out if wind slabs will trigger can be challenging. Instead, we typically use visual clues to locate and avoid the hazard. You’re most likely to find these firmer slabs along ridges, below cliffs, in the tops of chutes, and on exposed mid-slope features. With the increasing S-SE winds, you could encounter slabs in some strange places. Make sure to plan for the potentially complex and overlapping wind loading patterns. With all the new snow, expect slabs to be bigger and more dangerous as you ascend in elevations.

    (1/8/2024)

    Example: This wind slab sat right at the base of a cliff.

    Photo: Trevor Kostanich

Avalanche Discussion

The new snow seems to be healing quickly. This isn’t too surprising given the cooling trend but relatively warm temperatures. Several avalanche professionals around the zone on Thursday reported a generally right-side-up upper snowpack. This, combined with a lack of concerning layers in the storm snow, should limit the avalanche hazard to wind-affected terrain. That doesn’t mean you can’t trigger a slide in non-wind loaded snow, but it would probably be localized to unsupported cliffy areas and loose slides (sluffs) on very steep slopes. 

One thing to keep your eye on Friday is the sky. You’ll probably see moments of sunshine. Suddenly warming temperatures could cause some tree bombs and rollerballs. If these blobs entrain snow, then expect a few small loose slides. At lower elevations, the minimal amount of new snow should limit the hazard, but higher up, these slides could be sizable. 

The magic line at the Pass seems to be around 4500ft. Above that elevation, the surface snow is much colder and drier. Below, expect a few inches of wet snow and maybe some crusts. This corresponds well with the overall rain-snow line during the meat of the storm.

We don’t anticipate any slides breaking into older, deeper snow layers. However, nearby zones East Central and West South saw persistent slab avalanches in the past few days. It’s not out of the question to think a wind slab avalanche or cornice could step down to the 2/19 interface or Early February Crust. If that happened, look out! It would release a huge avalanche. Don’t linger in the tracks or runouts of bigger paths.

Lastly, the middle and upper elevations received a lot of snow over the past week. Deep snow immersion and tree wells are once again a concern. Keep your partners in sight, and make sure you have a plan to communicate.

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