Boletín de aludes

Galena Summit & Eastern Mtns

Sawtooth 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 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Triggering a large, destructive avalanche is more likely here than in neighboring zones. You're most likely to trigger a slide on slopes with wind drifts or stiffer snow at or near the surface. You can significantly reduce your risk by choosing terrain that is sheltered from the wind. As the day warms up, wet snow avalanches are possible on very steep slopes that face the sun.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    In neighboring zones, the persistent slab problem has faded to join the list of minor concerns. The Galena Summit & Eastern Mountains are an unfortunate outlier. Here are the two main weak layers that are worth tracking:

    1. Weak, grey, sugary facets and crusts on shaded NW-N-NE-E facing slopes at middle and upper elevations. This layer sits near the ground under 3-5 feet of snow.  Watch Ben's video from the White Clouds on Tuesday where he describes a snowpack that's "capable of creating large, destructive avalanches".  It's been less than a week since our last major loading event and SAC staff and local professionals continue to avoid avalanche terrain where this layer is known to exist. 
    2. A subtle layer of crusts and facets beneath the recent storm snow may exist on some steep, sunny SW-S-SE facing slopes. This layer produced several 2-4 foot thick avalanches during the storm. This layer is likely quickly improving with warm temperatures and a lack of additional loading. 

    This large, natural avalanche released naturally near the end of the last storm in very steep, rocky, wind-loaded upper elevation terrain in the 4th of July drainage in the White Cloud Mountains.  

Avalanche Discussion

IT'S DIFFERENT HERE

You're likely to see splashes of green (LOW danger) appear in the next couple of days on many elevation bands in the surrounding zones. In this zone, we're much more hesitant to go there. Why?

  1. The weak layers are proven. Avalanches failed on weak layers near the surface and at the ground during our last storm. 
  2. The weak layers are ugly. Sugary facets remain weak and continue to produce unstable snowpack test scores. 
  3. The weak layers are well distributed. Due to the overall higher elevation, old October snow is located in more terrain here than in neighboring zones. 
  4. More trigger points exist. This zone has seen enough snow to build a meaty, dangerous slab, but not enough to completely armor the weak layer from the impact of our weight. 

The combination of these factors adds up to keep triggering a persistent slab avalanche squarely on the table. It's also plenty of motivation to keep me and other local professionals off of wind-affected, "prime time" 35-45* slopes where this weak layer exists.

In addition to the persistent slab problems listed above, there are a couple of other minor problems to consider when planning your day in the mountains:

Wet Loose Avalanches - Yesterday, wet loose avalanches were reported on very steep sunny slopes. These avalanches are possible again today as clouds part this afternoon. Wet loose avalanches begin at a "point", usually the base of a warm rock or tree, and fan out to collect snow as they go. They are most problematic in confined terrain or on large slopes where they gather a lot of snow. Rollerballs, or herds of small snowballs peeling off steep terrain, can be a helpful clue that the snow's surface is weakening and wet loose slides may occur. 

Wind Affected Snow - Southwest of this zone, Soldier Mountain Cat Ski staff triggered a sizeable avalanche with explosives on Monday (photo). If you go poking around on enough very steep, wind-sculpted slopes you may find small, isolated wind slabs that are sensitive to your weight. This problem can persist longer in areas where slabs rest on icy surfaces and thin layers of facets. This same, wind-affected terrain harbors very large cornices. Extended periods of near or above freezing temperatures may encourage these unpredictable, massive blocks of snow to sag and fail.

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