Boletín de aludes

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Peligro de aludes

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

Lo esencial

Expect loose snow avalanches in very steep, rocky terrain receiving direct sun. Triggering a large slab avalanche is most likely on steep slopes facing the northern two-thirds of the compass, especially in the southern part of this zone where the snowpack is thinner.

Problemas de aludes

  • Loose Wet

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

    This zone has recently received 1-2 feet of snow, increasing the odds of loose snow avalanches on all aspects. The largest of these are most likely on very steep, rocky slopes receiving direct sun. These slides often initiate near the base of trees and rocks, gathering snow and growing in size as they move downhill. Rollerballs, or pinwheels, signify that the snow is heating up, and wet avalanches may soon follow. 

    While most will start small, they will be plenty large enough to knock you off your feet and carry you into unwanted terrain. Even small loose snow avalanches are consequential above terrain traps such as gullies, creeks, and thick timber. Plan your day to avoid lingering under steep, sunny slopes when the sun is out.

    Wind slabs may have formed immediately beneath exposed upper elevation ridgelines and on the sides of cross-loaded gullies. The slabs could rest above weak crust/facet combinations on southerly aspects or small sugary facets on more north-facing slopes. They can be up to 2 feet thick and break wider than expected. 

    (2/18/2025) Sun-induced loose snow avalanches on Boulder Pk in the Boulder Mountains. Photo: Sawtooth Avalanche Center

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–2.5

    Slabs that formed in early February rest above a variety of ugly, widespread, weak layers (facets, surface hoar, crusts, and combinations). Before triggering an avalanche, you're unlikely to experience obvious signs of instability like snowpack cracking and collapsing or whumpfing. Persistent Slabs can release in surprising ways and break much wider than expected. You are most likely to trigger a dense, 2-4 foot thick avalanche where:

    • The slab is less than about 2' thick—relatively shallower spots may exist where the wind frequently blows, and the slab is not uniformly thick.
    • Any part of the slope you are on or connected to is steeper than about 35 degrees
    • The slope faces the northern 2/3 of the compass
    • A smaller wind slab or loose snow avalanche overloads the buried weak layers (problem above)

    (2/17/2025) Avalanche on Sun Mountain in a thin snowpack near Ketchum.  Photo: Sawtooth Avalanche Center

Avalanche Discussion

Given the recent snowfall and wind, continue to look for and avoid steep slopes with obvious recent wind loading or signs of instability, like snowpack cracking or collapsing. Sluffing in very steep terrain is possible in dry snow on shaded slopes but is much more likely on any very steep slope soaking in the sun. Be aware of where even small avalanches may take you; terrain traps increase the consequence of being caught or buried.

Triggering a large persistent slab avalanche involving deeply buried weak layers is unlikely but not impossible. You are most likely to find trouble where the slab is thin and buried weak layers are more easily affected by your sled, skis, or snowboard. The drainages around Smiley Creek are examples of locations where we suspect these thinner slabs exist. We've found fewer signs of instability in the deeper portions of this zone, including the northern and western Sawtooths and the western Smokys.

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