Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

While the likelihood of triggering an avalanche continues to decrease, weak unstable snow still exists in the upper snowpack. Unfortunately, you can’t tell if any one slope is safe or not. So, consider simply staying off of large steep open slopes to manage this danger.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    When we deal with persistent problems like this, the reality becomes an increased level of uncertainty bringing with it a higher level of risk. If you choose to travel on large steep open slopes, you simply accept that risk. Unfortunately, tracks on a slope don’t give us much information about that area’s safety. Instead you can reduce your risk in several ways. 1. Seek out smaller and lower consequence terrain. 2. Identify and avoid common trigger points like shallow areas in the snowpack, convex rollovers, and steep unsupported slopes. 3. When in doubt, simply avoid large steep open slopes. 

    A well-documented layer of buried surface hoar was observed all across the West South zone this week. It was found 10-18 in (20-45cm) below the surface on all aspects and elevations as recently as Friday 12/16. While snowpack tests can help you find this layer, they can not prove its absence on any single slope. Over the course of the past few days, this layer has shown less potential for a failure to propagate into an avalanche.

    (12/13/2022) Snow profiles on a N aspect of the White Pass backcountry. Photo: Dallas Glass

Avalanche Discussion

We should see a transition in the weather Saturday that results in no real impacts on the avalanche danger. Increasing clouds and strengthening winds will start to hint at an approaching weak storm system. While you may start to notice blowing snow in the afternoon, we don’t expect any significant new hazard prior to sunset. If you use the nice weather to travel into the higher elevations, keep this wind drifting on your mind in steep exposed terrain. 

Warm sunny weather this week formed a thin crust on steep southerly slopes. If skies remain clear, this layer could soften again Saturday. If clouds roll in early, it could create challenging travel conditions on these same slopes. In areas not receiving direct sunshine, cold dry soft snow still exists. Besides the presence of the 12/8 surface hoar layer, the snowpack appears well-settled and relatively strong. 

A fresh crop of surface hoar and near surface facets formed during the clear weather this week. We want to know if this layer gets buried intact. Your observations from Saturday afternoon will provide the best snapshot prior to more new snow. Share an observations to let us know what you found on the snow surface.

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