Bulletin d’avalanche

East Slopes North

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Friday won’t be a typical storm day. Anticipate unstable conditions and unusual avalanche activity. Stick to low-angle, conservative terrain that limits exposure to slopes that could produce avalanches.   

Problèmes avalancheux

  • Storm Slabs

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

    The most dangerous areas will be shaded northerly aspects, especially on leeward slopes at middle and upper elevations. Widespread weak facets on the old snow surface could make avalanches easy to trigger and they could break widely across terrain features. 

    The usual strategies and tricks you use to manage risk might not be so reliable given the variation in snowpack structure below the new snow. Some slopes might produce no avalanches or just the small slabs you might normally expect. Other slopes could beget unusual avalanches that propagate widely, release when you are in the middle of a slope, or might even be triggered from below.

    (12/26/2024)

    An example of a skier triggered avalanche on a convex feature. Delancey Ridge, SE, 5,200ft

    Photo: Forest McBrian

Avalanche Discussion

A major storm will begin and bring at least 9" of snow by the end of Friday. Southwest winds will be strong enough to drift snow at ridgetops. The storm will continue into the weekend.

You can keep your decision-making simple and enjoy the fresh snow in low-angle terrain. If you choose to venture into avalanche terrain, there's a huge range of variable old snow layers to consider. If you find the following, consider avoiding avalanche terrain:

  • The facets (and surface hoar) mentioned are above are the most obviously dangerous weak layer. You can find them on all northerly aspects, as well as, some shaded east and west aspects.
  • If you find buried surface hoar with no underlying facets, you'll be dealing with a uniquely dangerous scenario.

Other old snow surfaces include:

  • The surface of sun-exposed, southeast through southwest, as well as some east and west aspects, have transitioned to melt forms. You'll likely find slick crusts, which may not bond well to the new snow.
  • At upper elevations, old surface wil be textured and wind-affected.

 

For the past couple weeks, we've been tracking surface conditions. On Thursday, an observer on Silver Star Mtn found widespread weak, faceted snow near the surface of a variety of slopes. He also noted extensive wind texturing at upper elevations. 

If you get out in the mountains, let us know what you see by submitting an observation HERE or via the Avy App. 

Régions couvertes