Bulletin d’avalanche

Stevens Pass

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Expect the avalanche danger to rise through the day as new snow and wind build unstable conditions at upper elevations. Use extra caution on steep slopes above treeline where the wind deposits pillows of snow. Wet snow and rain may fall on low elevation slopes.

Problèmes avalancheux

  • Wind Slabs

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

    It will be easiest for you to trigger a wind slab avalanche above treeline. Avalanches will also be larger at upper elevations. Use caution on wind-loaded slopes that are 35 degrees and steeper, and especially at the highest elevation. Steer around convex rolls, thicker pillows of snow, and slopes with drifted wind features. The most likely places for these avalanches are immediately on the leeward sides of ridges and terrain features.

    Watch for southwesterly winds to transport incoming snow. Other signs that you can trigger an avalanche include cracks shooting through the snow and recent avalanches on similar slopes. You can dig quick test pits or use small test slopes to see how easily the snow slides before committing to bigger terrain.

    (12/19/2021)

    A crown from an avalanche (size D2.5) that ran on 12/18 in storm snow. Similar wind slab avalanches could occur on  Wednesday. Above treeline, NW, Chiwaukum range

    Photo: Matt Primomo

Avalanche Discussion

Expect avalanche conditions to change throughout the day and as you move through the mountains. The danger may be minimal first thing in the morning but could increase if a foot or more of new snow accumulates with gusty wind at upper elevations. Below 3,500ft, wet snow or rain could fall. At these lowest elevations, you may encounter moist surfaces or even small wet avalanches. We have a good bit of uncertainty with exactly how much snow will accumulate by the end of Wednesday. Additionally, southwest winds tend not to favor Stevens Pass and may produce varying degrees of transport at different elevations.

On Tuesday, warm temperatures moistened snow surfaces. Observers reported rollerballs on some steep slopes. A widespread cycle of avalanches occurred on Saturday, the 18th (up to size D2.5) around Stevens Pass. You may still find test results on a storm interface from the 18th, about 1.5-2.5 feet below the surface, but we don't anticipate this to be a problem for avalanches. A couple of crusts, buried in early December can now be found roughly 4-5 feet below the surface.

Régions couvertes