Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Fri
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2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

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.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    In neighboring zones, the persistent slab problem has faded to join the list of minor concerns. While unlikely, triggering a persistent slab avalanche in the Soldier & Wood River Valley Mtns remains a possibility. 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 2-4 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. 

    (1/3/2022) This large persistent slab avalanche was observed above the East Fork of the Big Wood River prior to the recent storm. It failed on facets (October snow) buried near the base of the snowpack.

Avalanche Discussion

If I were trying to trigger an avalanche in this zone, I'd be headed to a snowpack around 8,500-9,500' in the Soldiers. Maybe somewhere near Boardman Pass, looking for variably wind-affected snow depths on a cross-loaded slope that faces N or NE. Why?

  1. The weak layers are proven. Avalanches were observed on weak snow layers during both of the last two storms. 
  2. The weak layers are well distributed. Older, October snow was preserved on a few NW-N-NE facing slopes above 8,000' in the Wood River Valley, but it's much more prevalent near Dollarhide Summit and in the Soldier Mountains. 
  3. More trigger points exist. The Soldiers and Dollarhide received 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 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 - 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.

Regioni coperte