Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

It’s going to be a White Christmas at Snoqualmie Pass! If you’re heading out to enjoy the new snow, be sure to look for increasing avalanche hazard as you ascend in elevation and on steep slopes over 35 degrees. Keep your friends and family in sight and don’t let them fall into the deep snow where they could struggle to get up.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Wind-affected terrain will remain the most likely location for you to trigger large slab avalanches at Snoqualmie Pass on Saturday. Look for these slabs on the lee side of ridges, near the base of cliffs, or in gullies and chutes. Freshly formed slabs may be easier to identify by looking for textured surfaces or actively blowing snow. Where the challenge lies is in looking for the Wind Slabs that are now hidden below a few inches of freshly fallen snow. Feel for a change in snow depth or firmer snow below the surface as an indication that you are in wind-loaded terrain. Identifying the predominant wind direction by looking for freshly formed cornices or drifting behind natural features can give you clues as to the aspects where you need to take extra care. If you suspect a slope to be wind-loaded, best to give it a wide berth and choose an alternate path.

    (12/23/2021)

    Winds continually filled in tracks throughout the day at mid and upper elevations. Conditions like this indicate lots of blowing snow and the possibility for wind slabs in nearby terrain.

    Photo: Robert Hahn

  • Storm Slabs

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

    Thursday and Friday brought reports of shallow human-triggered Storm Slab avalanches at Snoqualmie Pass. These slabs have been soft and many propagated only a short distance, but they have been able to entrain additional soft snow as they descended. Many of the reported avalanches had similar characteristics to Loose Dry avalanches, and in some cases were difficult to decipher between the two. Regardless of what you want to call them, the end result is the same. As the snow continues to pile up, so will the size of these avalanches that are breaking in the new snow. These slides will be more likely on slopes over 35 degrees and you can use test slopes as a good indicator of how they may break.

    As of Friday afternoon, the recent storm snow has remained relatively unconsolidated. However, a 2-inch layer of weak snow (graupel) was found about a foot below the surface by multiple parties in the Alpental Valley. This weak layer has not been reactive yet due to the lack of a more cohesive slab on top. However, if the storm snow starts to consolidate and form a stiffer slab, the potential for larger slab avalanches will increase. Take a look at the surface snow with hand pits or with your shovel to determine if a stiffer slab has developed. If it has and you also find this graupel layer, be sure to head for lower angled terrain.

    (12/24/2021)

    Shallow slabs such as this intentionally triggered slab on 12/24 show that although the snow is predominantly light and fluffy, there are areas holding some cohesion. 

    Photo: Robin Pendery

Avalanche Discussion

Where it exists, the Solstice Crust was found around 2 ½ feet below the surface at Snoqualmie Pass on Friday afternoon. We expect most avalanche activity on Saturday to occur above this layer. As noted above, a layer of graupel is a potential weak layer in this recent storm snow and was found about a foot below the surface on Friday afternoon in the Alpental Valley. These depths will only be increased on Saturday as more snow falls around the pass. So far the snow has been light and fluffy, but that could change due to wind or fluctuations in temperature. Continue to watch for slab development as the snow piles up and the weather changes. With this much soft snow, even falling and not being able to get up can present a hazard. Keep your partners in sight and read up on snow immersion hazard here.

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