Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

As more snow accumulates, the avalanches danger should slowly rise. You may encounter pockets of wind-drifted snow, especially in the afternoon. Blowing snow and sharp thin cornices should help you identify wind loaded slopes you may want to avoid.

Problemi valanghivi

  • Wind Slabs

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

    Windy weather Friday could easily turn the modest amounts of new snow into a new batch of slabs. You’ll start to see these first at upper elevations and where more than 2-3 inches of new snow falls Thursday night. As more snow piles up, you may encounter this problem along exposed ridges and near the base of cliffs. Fortunately, the actively blowing snow and developing wind features should make them pretty easy to spot and avoid. While most of these slabs should remain pretty small, you could trigger larger avalanches in places that receive more than 6-8 inches of new snow by Friday afternoon. You’re most likely to encounter these greater snow totals and large slides on the volcanoes.

Avalanche Discussion

It may take a bit for the storm to really get going Friday and for the avalanche danger to develop. So, if you’re out in the morning, you may find lower hazard than forecasted. However, as the snow starts to stack up, the danger should slowly rise. This will happen at different times in various locations within the West South zone. Not surprisingly we’re anticipating Mt Rainier and Mt St Helens to see the brunt of this storm. This is where we expect the danger to be the greatest, however, even the crest locations will get in on the action as more snow falls. 

Going into this storm were generally concerned with avalanches failing within or at the base of the new snow (3/30 interface). Even though this storm appears to occur with lowering snowlevels, temperatures aren’t too cold. In places that receive more than 6-8 inches of snow, this could result in storm slabs if the new snow bonds poorly to the old surface. You can use up track tests and hand pits as you travel to see if the new snow fails suddenly or in slab-like blocks. 

We don’t know much about the snow surfaces prior to this storm in the West South zone. We expect that warm moist snow was prevalent at lower elevations and on sunny aspects. This could form a new crust that the new snow may struggle to stick to. This could result in avalanches that trigger easily. In other locations wind scoured snow, pockets of powder, and frozen avalanche debris may sit just below the storm snow.

The storm will continue Friday night. As it intensifies expect the avalanche danger across the zone to rise rapidly. 

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