Lawinenlagebericht

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Kernpunkte

Very dangerous avalanche conditions exist, from the valley floor to the mountaintops. Slides will be easy to trigger and will be large enough to impact the floors of major drainages. Large natural avalanches are likely. Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes. Avoid all avalanche terrain as well as terrain exposed to avalanches from above. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–3

    Natural and human-triggered avalanches failing on a widespread layer of weak snow are very likely today. This weak layer is now buried 3-4 feet below the snow surface; any avalanche that fails on it will be very large and likely unsurvivable. Avalanches failing on this layer will break wider than you might expect, wrapping around multiple aspects and terrain features. A large natural avalanche failed on this layer yesterday, just outside the ski area boundary on Bald Mountain (pictured at right). The crown was 3-4 feet thick. This slide was on the small end of what is possible today.

    Steering clear of all avalanche terrain and terrain exposed to steeper slopes above is the only way to avoid this problem. Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes. Sluffing, cornice breaks, and storm and wind slabs can act as very effective triggers for this layer, "stepping down" to release very large and destructive slides.

    (12/11/2022) This large avalanche occurred just outside of the ski area boundary on Bald Mountain. The human pictured is 6 feet tall. The crown was 3-4 feet thick. It failed on the layer of weak, faceted snow that is widespread in our forecast area. This slope faces NW at 8,800'.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Certain
    Größe
    1.5–2.5

    2-3 feet of snow fell here in the past 3 days. Expect to find a range of storm-related avalanche problems today. Thick, dense, reactive wind slabs have formed and will be easy to trigger.  In sheltered terrain, enough cohesive snow has fallen to build touchy storm slabs large enough to bury you. Loose snow avalanches will be easy to trigger and will occur naturally during any periods of direct sunshine. Any snow that hasn't released naturally will be very easy to trigger today. Any natural or human-triggered slides failing in the new snow have a good chance of "stepping down" to the weak snow described above, creating very large avalanches.

Avalanche Discussion

Yesterday's storm caused an impressive array of avalanches. Visibility was very poor throughout much of the day, and our observations of avalanches in the mountains are non-existent. But we didn't need to go into big terrain to find avalanches, they were coming down to the valley floor to meet us. Here's a quick rundown of some of the observed activity: 

  • Della Mountain west of Hailey avalanched in many locations, with multiple slides running to the valley bottom. One slide blocked and temporarily diverted the Big Wood River (photos and more details here).
  • At least three houses were hit by avalanches around the city of Ketchum.
  • Warm Springs Road was hit by a large avalanche and blocked by a slide path that hasn't slid in recent memory. 
  • A large natural avalanche was observed just outside of the ski area boundary at Bald Mountain. The crown of this avalanche was 3-4 feet thick (photo).
  • Dozens and dozens of roof-alanches were observed. Though relatively small, these can easily be deadly. 
  • Highway 75 was hit by numerous avalanches. The road was blocked by avalanche debris and remains closed as of this writing at 4 AM.
  • A large natural avalanche failed above the East Fork of the Big Wood River around 1 PM on Sunday. The powder cloud came down to the valley floor.

The storm has largely drawn to a close but very dangerous avalanche conditions remain. Think of the snowpack like a house of cards. Over the past few days, heavy snowfall and winds added cards to our house. In many places the house collapsed and was quickly rebuilt by the ongoing storm. Today, our snowpack house is teetering on the edge. An intense spit of snowfall, an uptick in wind speeds, or a trigger (you), will be all it takes to make it come crashing down. Please, continue to be safe and make good choices. Today is not the day for avalanche terrain.

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