Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

A small slab avalanche was intentionally triggered on a steep, wind-loaded rollover on Sunday. With cool temperatures, conditions are not expected to change much, so steep, wind loaded areas are your main concern on Monday. Search out thicker, pillowed snow features, and although they may be quite soft, steer around these wind-loaded deposits on steep slopes. 

Problemas de aludes

  • Wind Slabs

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

    You could trigger an avalanche in the foot of snow that fell with wind on Sunday. Areas where wind deposited snow into deeper or heavier drifts is where you are most likely to trigger an avalanche.  The higher you go the more wind will have affected the snowpack, and you can expect to see wind slabs much deeper than the snowfall amount that we just had, resulting in larger avalanches.

    Search for "pillows" on steep rollovers. Deposits may build up just below ridgelines, or in gullies.  Another common location where you might be able to find wind drifted pockets is around rocky outcroppings. If you travel near any of these areas, pay attention to the snow in front of you and under your feet, and notice whether deposits get deeper, or slightly stiffer.  That subtle change could be enough for you to trigger an avalanche. Conditions right now are deceiving because temperatures are relatively cool and the new snow is quite light and fluffy. Snow that avalanches will likely be very soft. Avoid slopes steeper than 35 degrees where you notice wind slabs formed.

    Keep in mind that this low density new snow could sluff, or dry loose avalanche, in steep, non wind-loaded areas. Be observant of any sluffs you might cause if you travel out onto steep terrain. This could be the case in all elevation bands. 

    (12/18/2022)

    A small skier triggered wind slab avalanche which occurred early Sunday afternoon as snow totals and wind increased. Located on the lower Elbow in the Baker backcountry. 6-12" crown. SS - ASc - R1-D1

    Photo: Adam U

Avalanche Discussion

We may see cloud breaks in the North Cascades, so despite our close proximity to the winter solstice and cool temperatures, keep small, shallow wet loose avalanches on southerly slopes on your mind for Monday. Previous to this storm, surface hoar was present on the surface in many locations. It most likely remained preserved in areas that were sheltered from the strong winds we saw in the last week. This is primarily in near treeline and below treeline areas. In these locations, surface hoar may lie preserved beneath the new snow layer. This means that triggering an avalanche could be easier than you thought it would be, or an avalanche could span further than expected if triggered. The new snow layer is shallow enough that you can dig with your hand down to the bottom of it, and see if snow breaks easily at the interface. You might be able to identify a layer of surface hoar between the new and older snow layers. It is not expected that surface hoar would have stayed preserved on south-facing aspects, where you're more likely to find a crust instead.  Although wind events occurred several days ago, there is a small chance you could trigger a deeper avalanche on an older, harder wind slab. This is especially the case if you make your way to higher elevations. 

 

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