Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
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, a weak snowpack, and overlapping avalanche concerns should create dangerous conditions Thursday. Choose simple, low consequence terrain where you have lots of options to avoid the avalanche hazard. Some slides could involve deeper snowpack layers and grown much bigger.

Problèmes avalancheux

  • Storm Slabs

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

    You might find that these storm slabs don’t heal up quite as quick as normal. In some spots the new snow may sit on top of weak facets or surface hoar. Telling exactly where, those nasty grains hide will be nearly impossible. You’re most likely to trigger avalanches where the new snow overlays persistent grains, in wind-loaded areas, on convex slopes, and in unsupported terrain. 

    Hand pits, small slopes, and uptrack tests can all help you get a feel for the storm slab issue. However, since the snow surface was so variable prior to the storm, determining how any particular slope will reach could be nearly impossible. If you’re going to venture into steeper areas, look for slope with clean runouts void of rocks, trees, and gullies.

    (1/17/2024)

    Example: A small skier triggered slide that failed on the 1/16 interface. 

    Photo: Dallas Glass

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    We don’t know much about the Deep Persistent Slab problem in the East South. However, avalanches to the north (East Central) and to the west (West South) make it a pretty good bet. Needless to say, this fresh snow won’t magically make this menacing layer go away. 

    Weak facets exist on and within a number of crust layers buried deep in the snowpack. Slides could easily be 2-4ft thick! 

    A smaller storm slab, cornice failure, or just hitting the wrong spot could cause the entire slope to come unglued. Sure, it’s not very likely, but the consequences are immense. Talk about this issue before you set foot in any part (start zone, track, or runout) of avalanche terrain.

    (1/14/2024)

    This widely propagating avalanche occurred near Sourdough Gap/Morris Creek near the boarder of the West and East South zones. 

    Photo: Dan Royal

Avalanche Discussion

A short lull Wednesday night will give the snowpack (and us) a second to breath. However, more snow is on the way Thursday. You could see another 6in, or so around most of the zone. This would bring storm totals to 8-15in. 

We didn’t any new information from the East South zone Wednesday, but in near by Crystal Mt avalanche professionals reported pockets of wind drifteted new snow even well below ridgeline. This resulted in one skier triggered slide. Near Hwy12 (White Pass) small natural storm slabs released along road cuts. In both cases the avalanches were generally small but they speak to the instabilities of the new snow. 

You could sum up the snowpack concerns into three main topics: 1). Avalanches within the new snow (generally small), 2). Slides failing on the 1/16 interface, including facets and surface hoar. These avalanches would be bigger and could trigger easily. And 3). The Solstice Matix. A weak facet/crust complex often 2-3ft (60-90cm) below the surface.

Régions couvertes