Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You could trigger wind slab avalanches at upper elevations. Loose wet avalanches could run on steep slopes that face the sun. The potential size of avalanches will increase as you gain elevation and move closer to the Cascade crest, where more recent snow has fallen.

Problemas de aludes

  • Loose Wet

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

    Warming temperatures and sunshine will keep loose wet avalanches running on very steep, sun-exposed slopes. Look for signs of loose wet activity such as rollerballs, and other small fan-shaped avalanches as temperatures warm. The potential size of loose wet slides will increase where you find more than 8" of new snow, such as the mountains northwest of Cle Elum. Don't let these predictable avalanches catch you by surprise in or around terrain traps or extreme terrain.

    Loose dry avalanches are possible on very steep slopes in the shade. Ride cautiously in steeper terrain knowing that you could initiate sluffs that may entrain loose snow and grow larger.

    (3/24/2021) An example of small loose avalanches near Washington Pass. Photo: Josh Hirshberg

  • Wind Slabs

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

    Strong westerly winds have been transporting the new snow onto lee slopes. Winds may have created slabs further downslope or below ridgelines. Avalanches will be larger on higher elevation slopes and near the Cascade crest where snow accumulated. Look for signs of instability such as shooting cracks, and stiffer textured snow over weaker snow. Feel for textured wind-affected snow as you change aspect and elevation. 

    Give cornices plenty of room when traveling on ridges and stay out from under them.  Travelers are surprised every season when cornices break further back than they expect. 

    (3/22/2021) Small wind slab release on a test slope. Notice the rippled texture to the snow surface.

Avalanche Discussion

As is typical for the East Central zone, snowfall totals vary widely from Wednesday's storm. Near 8" accumulated in the southwest portion of the zone and snowfall amounts taper off to 1" for areas to the north and east. At Mission Ridge, westerly winds were strong on Wednesday with gusts into the 60's. The new snow fell on a mix of sun crusts on the east to south to west aspects and cold dry snow surfaces on northerly aspects. Small near-surface facets were observed above treeline in the neighboring Stevens Pass zone last week, prior to the last two storms. On Monday, an observer in the Van Epps Pass area found around 8" of new snow. 

A crust and adjacent weak layer formed in mid-January can still be found about 2-6 feet below the surface throughout most of the zone.  Several different avalanche cycles released down to this interface, with the last cycle producing avalanches up to size D4.  Avalanches on the mid-Jan crust/facet layer are now unlikely with the last one reported on March 1st.  We're watching the upcoming weather pattern for major warm-ups or storm events to see when and if these deeper layers will be tested again. The most suspect areas for deep persistent slabs are shallow, rocky, and unsupported slopes, especially where overhead cornice fall could trigger avalanches.w

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