Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Avalanches are most likely in areas where wind loading has formed drifts or stiffened the snow surface. Although less likely, avalanches are still possible in areas sheltered from the wind. You could trigger slides remotely—from flat terrain below, above, and to the sides of steep slopes.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–3

    You are more likely to trigger a large, persistent slab avalanche on steep slopes with recent wind loading. Wind loaded slopes are most commonly found at upper elevations. Triggering an avalanche is less likely—but not out of the question—on steep slopes that are completely sheltered from the wind.

    Snowpack cracking and collapsing or whumpfing are clear signs of unstable conditions. However, a lack of these obvious warning signs doesn't mean you're in the clear. The slabs in question rest above a variety of weak layers (facets, surface hoar, and crusts + facet combinations) and these layers are widespread.

    Avoiding steep, wind-loaded slopes can significantly reduce your chances of triggering an avalanche. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered.

    Additional Discussion: You may be able to trigger wind slab avalanches that formed near ridgelines and in cross-loaded areas on the sides of gullies. The size and chance of triggering these slides increase significantly as you climb into windier, alpine terrain at upper elevations. These avalanches could step down to the buried weak layers described above. Watch for snow pillows, dunes, and ripples, and feel for stiff snow under your feet or sled. These are signs the wind has been at work transporting snow.

    (12/31/2024) Explosives-triggered slab avalanche on a NE-ESE facing bowl @ 8,400'. The avalanche broke ~300' wide and 2-3' deep.  Shoulder of Peak 2 in the Soldiers. Photo: Sawtooth Avalanche Center

Avalanche Discussion

You may have noticed a handful of Moderate danger ratings creeping onto the forecasts over the past day or two. These should be tentatively viewed as “spicy” moderates. What does “spicy” mean? We’re trending towards a low-likelihood but high-consequence scenario. Your odds of triggering an avalanche are slowly decreasing, but, if you do trigger one, the consequences would be severe. 

These slabs come in a variety of thicknesses throughout the forecast region currently, but we can distill them into two general flavors:

  • In areas where the slab is less than ~3 feet thick, the hazard is more obvious. You may observe instability with more frequent observations of cracking, collapsing, and avalanches.  Shallower snowpacks are most commonly found in the Soldier, Boulder, and Pioneer ranges, as well as the mountains around Ketchum and Galena Pass.
  • In areas where the slab is thicker than ~3 feet, the hazard is less obvious. You may receive fewer signs of instability from the snowpack in terms of avalanches, cracking and collapsing. Persistent slab avalanches may be getting harder to trigger in these locations, but the resulting avalanches are expected to be very large. You may not get feedback before triggering one of these large, destructive avalanches. Deeper snowpacks are most commonly found in Banner, the Western Smokys, and the Sawtooth ranges.

So how do we operate under these conditions? Proceed with caution and approach the mountains with the assumption that avalanches are possible on many aspects. Take note of differing surface conditions and, especially, wind-loaded slopes. Manage your group by riding or crossing steep slopes one at a time, and consider avoiding areas where terrain features like gullies, cliffs, or dense trees could increase the consequences of a slide.

Regioni coperte