Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

A few natural wet avalanches could still occur Wednesday even as temperatures cool and precipitation tapers. These slides are most likely in steep rocky terrain. Pay attention to the areas above you and limit your time below these slopes.

Problemi valanghivi

  • Wet Slabs

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

    Several days of rain high into the alpine thoroughly wet the snowpack to the ground in most areas. As water drains it could release isolated wet slides that take any number of forms: wet slab, glide, and loose wet. These types of avalanches and this set-up is notoriously challenging to assess and predict. 

    While avalanche activity should decline, you could still encounter slides, particularly in steep rocky terrain. In this case, triggering a slide is possible, but the potential for isolated natural avalanches is more concerning. Don’t linger below steep rocky slopes that still hold snow. These features could shed with little or no warning.

    (1/15/2023) Example: A large wet slab avalanche that released from steep rocky terrain during a similar rain event last winter. Photo: Dallas Glass

Avalanche Discussion

The storm should start to taper off Tuesday night into Wednesday morning. However, it will take more than a small dip in temperatures to heal the wet and weak snowpack. Wet avalanche issues can linger even as snowfall returns. At upper elevations, new snow may start accumulating later in the morning. We don’t expect much in the way of new dry snow problems, but you could encounter very small isolated pockets of wind-drifted snow. 

One of the greatest challenges Wednesday will be travel conditions. Wet punchy snow, roaring creeks, open holes, and exposed obstacles abound. 

The past week is one to remember. We’ve gone from a very shallow, almost non-existent, snowpack on Wednesday to depths nearing 4-5 ft. A pair of intense high-elevation rain events then washed much of this snow away. Weather stations indicate many areas lost roughly 50% of their snow (12-20 inches). 

Observations have been very limited and we still don’t know the full extent of the impact from these storms. On Tuesday the USGS reported a few large (D2) and very large (D3) avalanches on Mt St Helens. These slides occurred 12/2- 12/4 on multiple aspects at upper elevations. Past that, we know very little.

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