Bulletin d’avalanche

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You could trigger a 1-3 foot thick avalanche in areas where the wind has formed drifts or stiffened the snow surface. You are less likely to trigger avalanches in wind-sheltered areas. To reduce your risk, you can stick to smaller terrain and avoid areas with thick trees, gullies, or cliffs, as these features can increase the consequences of even a small slide.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2

    What and where is it: Near ridgelines over about, 8500, you could trigger soft or stiff, 1-3 foot thick slabs where wind formed drifts or stiffened the snow surface. You are less likely to trigger avalanches in wind-sheltered areas. The widespread nature of various weak layers (facets, crust-facet combinations, and possibly surface hoar) means avalanches are possible on many aspects. 

    How can you recognize it: Signs of instability include cracking, and collapsing or whumfing, are clear signs of unstable conditions. Look 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.  

    How can you manage it: To reduce your chances of triggering an avalanche, avoid steep, wind-loaded slopes. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered. Remotely triggering an avalanche from flat terrain below steep slopes remains possible.

    (12/21/2024) Skier-triggered avalanche near 9800' on a NE aspect in the northern Boulder Mtns.

Avalanche Discussion

You are most likely to trigger small or large avalanches near or adjacent to ridgelines, or in alpine terrain where the wind has built drifts or stiffened the snow surface. Snowpack cracking or collapsing are clear indicators that the weak layers buried in mid-December are capable of producing avalanches. The mountains have been relatively quiet recently, with only a few natural avalanches and one human-triggered avalanche reported. However, with a poor snowpack structure and ongoing signs of instability—cracking and collapsing—we know that triggering avalanches is still on the table.

Recent observations highlight this:

  • Yesterday, skiers on Titus Ridge observed actively drifting snow and ridge top scouring. 
  • Monday, a professional observer in the Banner Summit zone noted several "muffled" collapses in both sheltered and wind-affected terrain. 
  • Monday, in the Sawtooth mountains, Scott saw a large natural avalanche on the SE face of Decker Peak that likely happened last week, but it serves as a good reminder of the potential size associated with the persistent slab problem.
  • Sunday, a forecaster experienced several snowpack collapses—some in excess of 100 feet—in wind-loaded terrain in the Headwaters of the Salmon/Frenchman Creek area. 
  • Saturday, a group reported a human-triggered avalanche in wind-affected terrain near 9800 feet on a NE aspect in the northern Boulder Mtns (Galena Summit & Eastern Mtns zone).
  • Saturday, professionals in the Banner Summit zone (NE aspect near 8800' on Copper Mountain) reported a large collapse that sounded like a shotgun.

Manage your terrain today by avoiding areas with obvious signs of wind loading. You can further reduce your risk by choosing simpler terrain with clean run-outs, free of any terrain traps, and only exposing one person at a time to potential hazards. 

Régions couvertes