Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Shifting winds over the past couple of days and a few inches of fluffy snow could make spotting and avoiding wind-loaded areas trickier than normal. Assume most exposed slopes have some sort of wind effect until you are sure otherwise. Steer around any feature where you think the winds formed deeper drifts

Problemas de aludes

  • Wind Slabs

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

    Anticipating the wind-loading pattern could be hard on Tuesday. Many of the classic clues we often look for could be hidden or misleading. Instead, you’ll probably need to assume wind slabs are present especially near exposed ridges, along the base of cliffs, and in chutes. 

    You could find firmer deeper wind slabs on a variety of aspects and in some odd spots due to the recent shifting winds. With the potential for such a weird loading pattern, consider steering clear of high consequence terrain where mistakes will likely have more serious outcomes. 

    Wind events over the past few days built several rounds slabs. Some of the fresh drifts may trigger easily but should be relatively small. Conversely, older slabs may be hard to trigger but could be larger and break above you.

    (1/20/2023)

    Example: Even if you can't see the wind slab, assume they are in terrain like this Tuesday. 

    Photo: Paris Gore

  • Loose Dry

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

    Plenty of soft fluffy powder awaits you outside of wind-affected areas. Unfortunately, this new snow seems to be poorly bonded to the old surface. This could result in easy to trigger loose dry or very soft slab avalanches that run far and fast. While these slides should stay relatively small, some of them could grow large enough to knock you off your feet and take you for an unwanted ride.

    If the sun comes out in the afternoon, snow may shed from rocks and trees initiating a round of natural loose avalanches. 

    (11/28/2022) Example: Intentionally triggered loose dry avalanche in the White Pass backcountry. Photo: Dallas Glass

Avalanche Discussion

While not a huge storm, the recent weather definitely favored the West South zone. As of Monday afternoon, weather stations were reporting 8-16 inches of snow since Saturday night. This snow fell with cold temperatures and often resulted in very low-density powder. 

More snow is expected Monday night into Tuesday. Places like Mt St Helens could pick up another 10-12” of snow and result in locally dangerous avalanche conditions. 

Prior to the storm, nearly every imaginable snow surface was reported. Icy crusts, wind-textured snow, soft powder, surface hoar, and sugary facets were the most common. Not surprisingly, this variability makes it a bit harder to predict how any particular slope could respond. An NWAC forecaster in the Crystal backcountry Monday found that despite this variability the new snow was generally poorly bonded to the older surface. 

Stormy weather and poor visibility have limited recent observations. The only avalanches we’ve heard of during this storm were from White Pass, where the Gunsight Chutes (NE, 6200ft) produce several natural wind slabs 6 in deep. At the moment we expect avalanche activity to fail at or above the new/old interface (2/25). While we can still see older snow layers, and even find pockets of weak snow, we haven’t seen any avalanches occurring deep in the snowpack.

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