Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You should find generally safe avalanche conditions at the Pass Saturday as we start to transition from sunny weather into a more stormy pattern. Increasing winds may begin to form shallow fresh slabs at upper elevations by the end of the day. Watch for blowing snow to help locate drifted features you want to avoid.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    You may notice wind speeds steadily increasing throughout the day and beginning to transport snow onto lee slopes. Fortunately, there’s not much snow available for the winds to drift. This should help limit the size and scope of this problem. However, thin fresh slabs may form at upper elevations and on exposed features by the early afternoon. You should see obvious clues, like blowing snow along ridgelines, that tell you to pay attention. Even though we expect any avalanche to remain small, they could trigger easily. Don’t let one of these thin slabs knock you over in high-consequence terrain.

    (12/3/2022) Blowing snow will be your most straight forward clue for new wind slabs. Photo: Dallas Glass

Avalanche Discussion

Saturday will be a bit of a transition day. After a week of high pressure, a small storm system will start to arrive at the Pass. Even though you may see a few showers in the afternoon, cloudy skies and increasing winds will be the primary impact. This could allow the avalanche danger to rise slightly later in the day. 

For the past week, we forecasted persistent slab avalanches at the Pass. We removed this problem from the weekend forecast even though the snowpack structure still exists. A lack of avalanches and recent significant snowpack test results continues to give us confidence. At this point, the chances of triggering a slide on this persistent layer seems very low and would likely be an isolated event. If you want to look for this layer, you may find buried surface hoar or preserved stellars (snowflakes) about 12-18in (30-45cm) below the surface. Often snowpack tests are needed to highlight this layer. Even though we’ve removed the problem, if you see shooting cracks or feel sudden collapses, stay off of nearby steep slopes. 

Warm sunny weather this week formed a thin sun crust on many steep southerly slopes. Cloudy skies should prevent this layer from softening Saturday and could create challenging travel conditions. On more shaded slopes, cold dry soft snow continues to linger. 

A fresh crop of surface hoar formed this week (see photo). As we head into this next storm we want to know if this layer becomes buried. Share what you find by submitting an observation. Today’s snow surface can become tomorrow's weak layer.

Régions couvertes