Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Steady winds will continue to blow new snow into wind-drifted slabs at middle and upper elevations. You can avoid this problem by looking for sharp drifts, fresh cornices, or pillow-like slabs on the snow surface. Steer around steep wind-drifted slopes if you notice signs of instability, like shooting cracks under your feet or sled.

Problemas de aludes

  • Wind Slabs

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

    Moderate east winds will change more southerly and continue to drift snow into cohesive slabs on leeward features. You’ll typically find these wind slabs just below ridgelines, cornices, and under rock/cliff bands. However, recent east winds may have drifted snow into unusual locations, such as west aspects or across terrain features (cross-loading). So, actively look for these slabs as you change aspects. 

    You can use visual clues to help you identify the hazard. Look for sharp drifts, pillow-like slabs, or dunes at the snow surface to help you spot where the wind has been at work. These slabs could break in surprising ways if they overlay surface hoar, facets, or recently buried crusts. Use small test slopes or hand pits to gauge how reactive the slab is. Consider steering around steep wind-loaded slopes if you notice active drifting or signs of instability, such as shooting cracks or hollow-sounding snow. 

     

    Use small test slopes and look for signs of instability like this before committing to steeper slopes. 

    Photo: Joe Dellaporta

Avalanche Discussion

Thursday will bring increasing freezing levels and light mixed precipitation below 5000 ft. Above this, precipitation should stay dry. As temperatures rise, watch for rollerballs and small wet loose avalanches. These likely won’t grow too big or widespread, but consider steering around larger slopes if you notice these signs. 

NWAC Forecasters traveled to Mission Ridge on Tuesday and found the layer of surface hoar from the solstice to be fairly widespread, and large in some places. It was up to 2cm thick in one profile on a NE aspect at 6,500ft! (see photo below). Wind slabs were on the small side and localized to ridgelines, but nevertheless small ones were reactive. Another observer in the western edge of the zone (upper Icicle) found a more uniform snowpack and largely non-wind affected snow. The sun likely created a thin crust on steeper slopes that face SE-SW.

The recent snow is helping coverage, but can also bury obstacles, leaving them lurking just below the surface. With plenty of brush to contend with off the trails, exposed boulder fields, and rocks on many slopes, consider using summer trails or roads to access higher elevations. 

You can contribute to the forecast! Let us know what you found by submitting an observation HERE. 

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