Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The storm continues, overloading a weak and complex snowpack. You could easily trigger large and dangerous avalanches in the recent snow. These avalanches may step down to deeper weak layers and break widely across terrain features. Limit your exposure to large open terrain, make conservative choices, and enjoy lower angle slopes instead.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Sensitive storm slabs were widespread on Thursday, and up to 8-10 inches more snow may fall overnight. With increasing temperatures creating an upside snowpack, it's already a recipe for avalanches. But you may also find these storm slabs don't heal as quickly as usual. In many areas, the new snow rests on weak facets or surface hoar. Telling exactly where those nasty grains lurk will be nearly impossible. But you're most likely to trigger avalanches where the new snow overlays these weak 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 would react could be very challenging. Look for signs of instability, like recent avalanches or shooting cracks, as a warning to stick to lower-angle terrain. If you're going to venture into steeper areas, jump on some smaller test slopes first and find slopes with clean runouts void of rocks, trees, and gullies.

    (1/7/2024)

    Shooting cracks ahead of your snowmobile are a sure sign of unstable snow. 

    Photo: Joseph Labernik

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    We know very little about the persistent slab problem in the East South. However, previous avalanche activity on persistent layers in East South and avalanches to the north (East Central) and the west (West South) make it a good bet this tricky problem also exists here. All this recent snow could be the tipping point for the deeper instabilities. Weak facets exist on and within several crust layers buried deep in the snowpack. Before the storm earlier this week, multiple groups triggered small slabs on a buried surface hoar layer (1/2). These avalanches could now be 2-4ft deep! A smaller storm slab, cornice failure, or just hitting the wrong spot could cause the entire slope to slide. Sure, you're more likely to trigger a storm or wind slab, but the consequences of one of those stepping down to one of these deeper persistent weak layers could be unsurvivable. 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

Storm totals on Thursday were between 6-10 inches, with the most falling near the Cascade Crest in the Hwy 12 corridor. We haven't had much recent info from East South since last weekend. But on Thursday in East Central, widespread sensitive storm slabs failed on the 1/16 interface of weak faceted snow. On Wednesday, Crystal Mt avalanche professionals reported pockets of wind-drifted snow even well below the ridgeline. This resulted in one skier triggered slide. Near Hwy 12 (White Pass), small natural storm slabs released along road cuts. These avalanches were generally small, but all these observations 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.

Regioni coperte