Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Once the sun starts breaking through the clouds and temperatures rise, expect snow conditions to change quickly. You’ll probably see plenty of roller balls, snow shedding from trees, and small wet avalanches. Pay attention to what’s above you and don’t let one of these smaller slides push you into a creek or over a cliff.

Avalanche problems

  • Loose Wet

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

    Sunshine, warming temperatures, and decreasing winds will help the snow surface become wet and sticky on southerly aspects. Once this happens, expect snow to shed from trees and rocks triggering lots of new roller balls and several small loose wet avalanches. While we don’t anticipate most of these slides to grow very large, a few could entrain enough snow to catch and carry the unwary traveler. So, pay attention to what’s above you, and once you start seeing snow rolling downhill, limit the time you spend on or under steep sunny slopes. 

    Anytime we see a big swing in the weather like we’re expecting Wednesday, we often see trees and rocks shed their loads. This could include cornices falling naturally. While there aren’t as many cornices out there as we often see in other years, and most are smaller, you don’t want to be under one if it falls. Fortunately, the travel advice is the same. Keep an eye on the slopes above you and limit any time you spend under one of these looming waves of snow.

    (1/19/2023)

    Example: A Wet Loose avalanche occurred as a result of a tree bomb during a period of sunshine on 1/19. [S 5200']

    Photo: Zack Novak

  • Wind Slabs

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

    Any lingering wind slabs are now a few days old and becoming harder to trigger, but they’re still out there. A rider-triggered slide near Keechelus Ridge Tuesday is a great reminder. If you’re going to find one, it will likely be on a steep unsupported slope or convex rollover. Before you jump into rocky complex terrain, take a look for clues that this could be one of those locations. Drifts, rime, and cornices are all great indicators pointing toward potentially wind-loaded slopes. Don’t let yourself get surprised by one of these small slabs where it could push you over a cliff or flush you down a rocky chute.

    (1/24/2023) Visual clues of possibly wind loaded slopes. Photo: Dallas Glass

Avalanche Discussion

Wednesday’s weather will be quite the change at the Pass. Anytime we’re looking at warm-ups like this, there’s a bit of uncertainty around how the upper snowpack will respond. A thin breakable sun crust that formed on Monday (1/23) should help soften the blow, but ultimately the snow surface should become wet and unstable. If wet avalanches begin to gouge and entrain significant snow, they could reach as deep as the MLK crust, grow larger than we expect, and travel further downslope.

Snowpacks at the Pass are very similar on SE-SW and W-N-E aspects. The main differences are the presence/absence of sun crusts at the various interfaces. Generally, we found 18-24 in (45-60cm) of snow over the very prominent and stout MLK crust. While snowpack tests often highlighted the most recent 1/21 interface, there just isn’t enough snow over this layer at the moment to pose much of a risk. Other possible weak layers (1/18 and just above MLK) were noted but seemed isolated and inconsistent. At the moment, we’re not worried about avalanches failing below the MLK crust. 

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