Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Monday should be the first break after a multi-day storm cycle. Give the new snow time to adjust. Start on smaller lower consequence slopes to see how the snow reacts. If you see any signs of unstable snow, step back and stay off of steep open terrain

Problemas de aludes

  • Storm Slabs

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

    Recent storms left a couple of feet of new snow, including several interfaces, and even a few thin crusts on sunny aspects. These layers should heal quickly, but don’t jump ahead too fast. Numerous avalanches were reported 3/11-3/15, including at least two partial burials in the zone. Times like this require patience. 

    Avalanches will be most common at upper elevations, in wind-loaded areas, on very steep slopes, and near convex rollovers. Ease into the terrain by starting on small steep slopes before moving to bigger or more consequential terrain. Use lots of test slopes, hand pits, and up-track tests. If you see it crack or fail in blocks, stick to lower angled or treed slopes. 

    While we’re most worried about the most recent storm snow, it's not out of the question for an isolated slide to break down onto older storm layers or even down to the atmospheric river (AR) crust. This would be most likely on larger complex, often rocky, slopes.

    (3/15/2025)

    A slab avalanche in Cement Basin that caught, carried, and partially buried a skier. They had skied several other runs without issue before triggering this slide.

Avalanche Discussion

Monday should provide a break after several stormy days. Generally sunny skies in the morning, could cause rocks and trees to shed some snow. This could result in a few natural wet loose slides. However, clouds are expected to come in quickly and shut down the wet loose action before it gets too crazy. Even still, the March sun is strong, the snow is fresh and cold, and cloud forecasting is tricky. If it’s sunny expect wet loose. If it’s not…well, don’t.

With all the new snow, there are plenty of potential interfaces and thin crusts to take a look at. Avalanche activity should be limited to the snow near and above the thicker AR crust. While all these inter-storm layers should be gaining strength they could be worth taking a look at. Unfortunately, our normal moving observations will likely only help you assess the most recent snow. A shovel and a bit of time will be needed to check out all of the upper snowpack. In many places, the AR crust is probably buried about 3-4 ft (100-120cm) below the surface. An NWAC forecaster near Crystal Mt on Friday found facets within the upper AR crust. We don’t know how common these weak grains are, but they are something to keep an eye out for if you’re digging.

On Mt St Helens and Mt Adams, the Saturday’s storm hit a little harder. In these areas closer to a foot and a half of new snow likely fell with strong winds. You could encounter dangerous conditions on any steep open slope. 

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