Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

Fri
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The West South zone remains in the bullseye of this winter storm. Even as precipitation starts to taper off and avalanche danger slowly declines, don’t let your guard done too quickly. Avoid common trigger points such as steep slopes below cornices, areas near rocks/cliffs, and convex rollovers.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    This storm had it all: significant snowfall, high precipitation rates, and fluctuating temperatures. Not surprisingly several layers formed within the new snow. Observations from Cyrstal Mt and White Pass Wednesday afternoon indicated these weaknesses were gaining strength and avalanches were becoming less likely. You may still trigger an avalanche within the new snow on very steep slopes and convex rollovers. Unfortunately, with more than a foot and a half of new snow (and counting) on the ground, some of our common storm slab observations like uptrack tests and small slopes, may not give us the information we need. Instead, take time to dig with your hand or shovel and look for strong over weak snow. If you can make it fail, give the snowpack more time to heal before venturing into steep consequential terrain.

    (11/30/2022)

    Hand pits like this can help you find strong over weak snow. 

    Photo: Christopher Van Tilburg

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    The winds during this storm weren’t super impressive, but they were plenty strong to transport snow and form slightly firmer wind slabs on a variety of slopes. You may encounter wind-loaded areas near ridgelines, on exposed features, under cliffs, and along gullies. What will be tricky is that most of these slabs will be hiding under a few inches of light fluffy powder. Curb your excitement and look for obvious clues that might help you anticipate and avoid wind-loaded terrain. Cornices, drifts, and the amount of snow in the trees can all help you hunt down this lurking beast. Since these avalanches may easily grow large enough to bury you, consider avoiding any steep open slope where you suspect the wind drifted snow. Seek out more sheltered or lower-angled slopes to stay clear of this sneaky problem.

    (11/30/2022)

    These shallow wind slabs failed at the base of cliffs and were intentionally triggered by Crystal Mt Ski Patrol. 

    Photo: Andy Harrington

Avalanche Discussion

This storm has been impressive in the West South. Many travelers reported fun and deep conditions. Snow totals range from 18-26 inches and we’re not done yet. Snow showers should continue to target this zone and bring an additional 6-8 inches by Thursday afternoon. While this won’t likely increase the avalanche danger, it may add some complexity to the already existing avalanche problems. 

Wednesday’s stormy weather prevented much in the way of observations. However, White Pass ski patrol reported a natural storm slab avalanche cycle that likey occurred during the heaviest precipitation in the wee hours of the morning. Avalanche professional at Crystal Mountain noted wind slabs near exposed ridges with more unconsolidated conditions in sheltered terrain. In both cases, the snowpack showed signs of gaining strength by the afternoon, with avalanches much harder to trigger. 

Even though this storm greatly increased the snowpack across the region, plenty of early-season obstacles remain. Open creeks, holes near rocks, and thinly covered brush continue to make travel at lower elevations tricky and more dangerous.

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