Boletín de aludes

Stevens Pass

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

The cool, snowy pattern continues. Heightened danger could be found at higher elevations, where the new snow is very deep and you're more likely to trigger a slab. Loose dry avalanches may entrain a surprising amount of snow on steep slopes at all elevations. Look for signs of instabilty like recent avalanches or shooting cracks, and choose terrain cautiously.

Problemas de aludes

  • Loose Dry

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

    As cohesionless snowfall accumulates, you might find that dry loose avalanches become frequent on steep slopes. These could entrain a fair amount of low density new snow, and pile up to be deep in some areas. At lower elevations they could run on older weak snow surfaces and firm crusts. Larger and steeper pieces of terrain could produce slides that pack more of a punch. Especially be careful of gullies and similar places where debris ends up.

    Example of natural dry loose avalanches.

  • Wind Slabs

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

    Avalanches could be larger at upper elevation where wind has sifted the snow enough to be a cohesive slab. Easterly winds blew on the 27th, and may have created slabs on open exposed terrain. With some new snow, these slabs may get buried and obscured so they could be difficult to identify. On Tuesday, the winds shift back to westerly, and could create fresh reactive soft slabs near higher ridgelines. Watch for drifts forming on cross-loaded features and gullies. Steer around large and obviously wind-loaded terrain right near ridgelines and cliffs, especially if you find shooting cracks, whumphing collapses, or strong over weak structure. 

    In very isolated areas, slabs could break wider and deeper than expected due to layers of buried facets, and a crust facet sandwich from mid February. Carefully assess the bond at recent interfaces, and how it changes as you travel. Use small test slopes and quick, informal tests to see how the snow reacts.

    (2/22/2023)

    Isolated cracking in pockets of wind-drifted snow near Lake Wenatchee. 

    Photo: Brooke Maushund

Avalanche Discussion

A few inches of very low density snow fell on Monday. Easterly winds were observed gently transporting snow. Control work at SPMR produced 12" deep, but generally small slabs. Sunday's front brought about a foot of new snow. Observers reported reactive conditions on steep slopes with loose dry, and soft slabs all running fast and far that day. Slides were all in the small range that we know of and not very deep. Last week, strong winds from the west and east created highly variable wind drifted surfaces. Very cold temperatures following an arctic front created weak surfaces on many slopes prior to getting buried on the 25th.

You can find a couple of crusts in the top half of the snowpack, and some weak snow surrounding them. A thin crust, buried on the 13th (now known as the Valentines Crust) is now 2- 3ft below the surface. 

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