Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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

As the snow continues to pile up at Snoqualmie Pass you may encounter larger and more widespread avalanches. As you ascend in elevation and leave the shelter of the trees, watch for places where recent winds formed firmer and deeper slabs. With growing and overlapping avalanche concerns, seek out terrain where you can easily identify and avoid steep open slopes. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Strong winds over several days easily transported snow at mid and upper elevations and likely formed slabs on the lee side of ridges, along exposed gullies, and near the base of cliffs. However, now these potential avalanches may hide under a few inches of soft snow, making any slope appear soft and inviting. Look for larger clues like drifts and cornices to figure out which way the wind blew and where slabs likely formed. You may also feel the change in the snow as you travel. Even if the surface looks soft, if you find stiffer snow, think “wind slab.” Because this problem is now harder to spot and could result in avalanches large enough to kill you, give any suspected wind-loaded terrain a wide berth.

    (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

    The cooling temperatures during this storm allowed the snow to fall generally right-side-up and bond well to the underlying crust. However, at some point you can’t ignore the growing snow totals and avalanche hazard they bring. On Thursday backcountry travelers triggered both soft storm slabs and loose dry avalanches in the Alpental Valley. Whether it's a loose or slab, at the end of the day it doesn’t matter. You can trigger avalanches in the new storm snow. As the storm totals increase these slides may grow large enough to bury and kill you. You may trigger storm snow avalanches on any open slope greater than 35 degrees. Use small steep slopes to see how the new snow responds to your weight. If you cause cracking or small slides this will help highlight the growing storm slab problem. 

    On Thursday several travelers reported graupel falling during the storm in the Alpental Valley(see photo below). Graupel often acts as a notorious weak layer for storm slab avalanches, but it can be very localized to specific mountains or drainages within a region. Hand pits can give you a quick glimpse into the snow. Look for small Beebee-like grains below the last 12-24hr  of snow. If you find buried graupel, it may be time to dial it back, and seek out lower angled slopes. 

    (12/23/2021)

    A small skier triggered soft slab avalanche on Snoqualmie Mountain.  SW, 4800', SS-AS-R1-D1-S

    Photo: Robert Hahn

Avalanche Discussion

On Thursday afternoon around a foot of storm snow had accumulated over the recent Solstice Crust/Interface at Snoqualmie Pass. This crust formed on Tuesday during warm sunny weather. As a result, it is most prevalent on southerly aspects and at lower elevations. As you ascend or move into shadier terrain, this interface still exists. We have not heard of any notable avalanches failing on this crust/interface in the Snoqualmie area. Observations generally report a good bond between the new snow and this interface. However, it can serve as a layer of interest if you dig into the snow. 

As temperatures become downright frigid, expect snow to water ratios to increase. You may find more snow on the ground than our weather station indicate.

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