Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
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

Underneath a couple of inches of new snow, older difficult to trigger wind slabs may still linger at mid and upper elevations. You’ll want to look and feel for these wind-loaded pockets. Steer around steep slopes below sharp drifts or where you find firmer hollow-sounding snow.

Problèmes avalancheux

  • Wind Slabs

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

    While you may find a few very shallow pockets of wind drifted snow from this current storm, they shouldn’t be large enough to pose much of a danger. The wind slabs we’re concerned about likely formed Monday and Tuesday. These much deeper and more dangerous slides could be hard to trigger but don’t write them off just yet. Because they’re now hidden under a few inches of new snow, you’ll need to stay sharp to find clues that help you know which slopes you want to avoid. The winds during the storm bounced between east, south, and west. As a result, you could find wind slabs on just about any aspect and in some unusual locations. Look for larger clues like sharp drifts and fresh cornices to point towards potentially wind-loaded slopes. You may also feel the snow change underneath you. If you notice firmer or hollow snow, expect wind slabs on similar aspects. When in doubt, you can always seek out less wind-affected or lower angled terrain to avoid this problem.

    (4/13/2022)

    Example of sharp drifts and wind sculpting to help indicate potential old wind slabs. 

    Photo: Andy Harrington

Avalanche Discussion

The southerly winds associated with this storm don’t favor locations like Snoqualmie Pass. As a result, we aren’t expecting too much in the way of new snow. So, even if the sun comes out on Thursday, you shouldn’t see more than a few piles of rollerballs or maybe a very small loose wet slide. These wet snow issues should stay limited to the new snow and not pose much of a risk. 

While we’ve been experiencing a relatively winter-like weather pattern, temperatures have begun to feel more seasonable and the snow level has crept up the mountains. The upper snowpack is marked by three crusts that can help you distinguish one series of storms from the next. The new snow should sit over a thin breakable crust buried on 4/20. This layer will be most pronounced on southerly aspects due to Tuesday’s brief period of sunny weather. Further down, the 4/18 interface is also typically marked by a crust, and should sit 6-12” deeper in the snowpack. The most prominent marker is the 4/8 melt-freeze crust that exists all across the zone and on every aspect. This signals the base of our upper snowpack. While we aren’t expecting avalanches on these layers, they are still on our minds as we head into a period of slightly warmer weather.

Régions couvertes