Boletín de aludes

Stevens Pass

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
3 · Notable
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

We're locked into a snowy pattern for the time being. Dangerous conditions should be expected at higher elevations, where the new snow is very deep and wind has created slabs. Loose dry avalanches may run fast and far on steep slopes. Look for signs of instabilty like recent avalanches or shooting cracks, and choose terrain with a conservative mindset. 

Problemas de aludes

  • Wind Slabs

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

    Avalanches could be more cohesive at upper elevation where wind has created thicker slabs. Westerly winds blew on the 25th and 26th and created slabs near ridgelines and on exposed features. With some new snow on Monday, these slabs may get buried and obscured so they could be difficult to identify. On Monday the easterly winds will begin to blow through the pass, drifting snow and creating fresh, reactive soft slabs. 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

  • 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 run far and fast on older weak snow surfaces and firm crusts at lower elevation. 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 could pile up deeply. 

    Example of natural dry loose avalanches.

Avalanche Discussion

Sunday's front brought a healthy dose of new snow, about a foot. Observers reported reactive conditions on steep slopes with loose dry, and soft slabs all running fast and far. Slides were all in the small range that we know of and not very deep. Ski penetration was becoming knee 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 about 2 feet below the surface. It's been almost 2 weeks (February 8-13th) since the last known avalanche on the MLK crust. It's in the middle of the snowpack, down about 3.5-5ft below the surface. The adjacent layers have gained strength and test results generally indicate less potential for avalanches. 

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