Boletín de aludes

Central Cascades

Central Oregon 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

On Saturday, it will be possible to trigger an avalanche on steep slopes where wind has loaded recent snow. This will be most likely on open leeward slopes, specifically below ridgelines and terrain features that block the wind. Evaluate snow and terrain carefully to identify and avoid these areas of instability. If in doubt of the snowpack's stability, stick to forrested or low angle terrain.

Problemas de aludes

  • Wind Slabs

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

    On Friday, I experienced an abundance of shooting cracks and pockets of reactive wind slab on steep, wind loaded slopes. This was primarily on any aspects with an eastern tilt (NE - E - SE). With winds dialing down for Saturday, there may not be much active blowing snow, making it less obvious to observe where these loaded slopes may exist. Look for visual surface clues such as ripples in the snow or pillowy drifts to identify loaded slopes. Below ridges and highpoints are common places where wind slabs can be triggered. As wind moves snow across open slopes, gully features in particular can become cross-loaded and filled in with new wind slabs. Cracking in the wind deposited snow and recent avalanches are excellent indicators of instability. If you notice these red flags, it is time to adjust your mindset and step back to more conservative terrain choices. Wind slabs can be avoided by sticking to sheltered areas (such as forrested terrain) or slopes that have been scoured by the wind. Keep in mind that open areas below treeline can be get enough blowing snow to create wind slabs.

    Cracking in wind deposited snow. Notice the rippled surface texture, a good indication of a wind loaded slope

    Photo: Ryan Marvin

Avalanche Discussion

The January 31st buried facet layer has been on many backcountry users radar this month. We have found this PWL to be more pronounced on sheltered and shaded aspects, i.e. NW-NE slopes at near treeline and below treeline elevations. Recent observations show this layer being 4F density and becoming less reactive in stability tests, now sitting nearly a meter or greater below the snow surface. With no recent avalanche activity reported on this PWL, it is currently on the far end of unlikely to trigger. Keep in mind that a large trigger (e.g. a smaller avalanche), could be enough load to step down to this layer. This would result in a much larger avalanche than would otherwise be expected.

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