Bulletin d’avalanche

Stevens Pass

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

New snow is stacking up, and winds have continued to blow it around. You could trigger large wind slabs near and above treeline on steep slopes with recent drifting. Expect another dynamic spring day, and conditions could change notably from morning to the afternoon with daytime warming.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    You'll find about a foot of new snow in the mountains, but in many areas snow depth could vary from recent wind drifting. Slabs could be thicker and larger near and above treeline. Look for signs of recent wind transport as you gain elevation, especialy as you near ridgelines and cornices. Look and feel for stiffer, cohesive snow. Pay attention to signs of instability such as long shooting cracks and other recent avalanches if you see them. Identify steep slopes of concern such as areas below cornices, and near rocks and cliffs.

    With daytime warming, snow surfaces may become heavier and more cohesive. Keep a lookout for wet and sticky snow surfaces during the day, and expect small wet loose 'pushalanches' to become possible if snow becomes moist and sticky.

    Wind drifts on exposed features like this could be reactive on Sunday.

    Photo: Matt Primomo

Avalanche Discussion

Sunday should be another spring snowy day. On Saturday, folks reported finding recent fairly wide but small natural avalanches in the SPMR backcountry, and were able to ski trigger small wind slabs mid-day. SPMR reported widespread but small storm and wind slabs with morning control work. Down at Snoqualmie Pass, many human triggered avalanches have been reported, most seemingly running on the old/new interface, often a crust. 

On Friday I went up Jim Hill and did find sudden failures at a late March interface. This same interface was the one that avalanched and caught two people last weekend on Lichtenberg. On Friday though, the grains were rounded, and didn't show potential to propagate with long column tests. This past week an easterly wind event damaged old snow surfaces and, the day of created reactive wind slab. The old snow surfaces that have been covered by the newer storm are a mixed bag of firm but rough sun crusts, soft wind etched or stiff wind board snow. 

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