Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

Sun
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Sunshine and warm temperatures will put wet avalanches at the top of your list on Saturday. You may see small natural slides on and below rocks and cliffs. However, once the snow becomes wet and sloppy, you might trigger a similar avalanche on any steep slope.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–1.5

    in the morning a thin crust should help limit the wet avalanche concerns. If you start and end your day early, that could significantly reduce this hazard. As the crust melts, wet snow will become widespread. Natural wet avalanches will be most common in rocky terrain receiving direct sunshine. Keep your eyes on what’s above you and limit the time you spend under these slopes. 

    As the snow surface becomes wet and sticky, you may trigger loose slides on any steep slope. These will be most common on E-S-W aspects, but the warm weather could help wet avalanches reach around to shadier parts of the mountains. In general, these slides should be small and easy to manage. Just don’t let them push you into a creek or over a cliff. 

    If you see slides breaking into slabs, gouging deeper, or growing larger, the scales have tipped, and you’re dealing with a much more dangerous wet avalanche beast. Put space between you and these slopes.

    (12/17/2023)

    Example: Fresh wet loose avalanche debris off of the cliffs above. As rocks warm quickly in the sun, wet loose avalanches become more likely.  

    Photo: Katie Warren

  • Wind Slabs

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

    If you head to higher elevation terrain, you will find areas of colder, dry snow. These will be most prevalent on northerly aspects. In these areas, wind slabs may linger from earlier this week. Look for textured surfaces, pointy drifts, and small sharp cornices to highlight local wind patterns and point toward loaded slopes. Be leery of firmer pillow-like drifts along exposed ridges, below cornices, and in the tops of chutes. It will be hard to tell if these slabs will or will not fail. Even though they should be small, they could be disastrous in high-consequence terrain.

    (1/7/2024)

    Example: Sharp drifts and small cornices along an alpine ridgeline help highlight wind-loaded slopes. [East Central]

    Photo: Katie Warren

Avalanche Discussion

After a mild but snowy week, we’re at the beginning of yet another springtime warm-up. This won’t be quite the shock to the snowpack as what we experienced earlier in March, but there will still be plenty of sunshine and warm temperatures. Spring conditions are also incredibly dynamic and hard to predict. Wet avalanches often catch travelers off guard. Additionally, the peak of instability may tip in different locations within the East Central Zone at different times. Toss on a lingering persistent weak layer, and you have all the makings of a rather uncertain situation, even if the danger rating doesn’t appear that concerning. Chose routes with lots of options, including easy was back to the car. 

With this warm-up we’re primarily concerned about the snow above the 3/21 crust. This more prominent crust is typically around 1 foot below the surface at middle and upper elevations. On Friday an NWAC forecaster found a layer of buried surface hoar within the recent snow. It's not clear how wide spread this layer is around the zone. A small skier triggered slide on Mission Peak, may have run on a similar weak layer or graupel over the 3/21 crust.

Even though we aren’t forecasting persistent slabs, the weak layer is still there. It’s been a few weeks since we’ve seen an avalanche on the facets over the Early February Crust. While not impossible, it is very unlikely you’d see an avalanche on this deeper layer. It would likely take a bigger trigger in higher elevation shaded terrain to result in a slide. If you’re traveling in these areas, factor that into your uncertain when discussing terrain. 

At lower elevations, the snowpack is thin and even sometimes discontinuous. Even though these snow down low is wet and weak, this helps all but eliminate the avalanche risk.

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