Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Human-triggered avalanches are possible. Slides are most likely on steep slopes where hard layers of wind-drifted snow sit at the snow surface. Avalanches can be triggered remotely—from below, above, and to the sides of steeper terrain.

Problemi valanghivi

  • Persistent Slabs

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

    Two prominent persistent weak layers are worth tracking:

    1. Facets and isolated surface hoar buried 1-2' down: The late January and early February storms and recent multi-day wind event produced many natural and human-triggered avalanches on this layer. It was the likely culprit in countless avalanches in the past 2 weeks, including the large avalanche in the Croy Canyon photo to the right/below. Last week in the Hyndman Creek drainage, Ben remotely triggered a very large, likely unsurvivable avalanche that appeared to fail on this layer before stepping down to weak snow near the ground.
    2. December facets, now buried 3-4' down: The good news—this ugly layer has become harder to impact as the burial depth has increased. SAC forecasters and others are seeing fewer obvious signs of instability (like collapsing of the snowpack). The bad news—the first sign of instability you see may be a large, unsurvivable avalanche like the one Ben remotely triggered in the Hyndman Creek drainage last week. This layer is trending towards a deep persistent slab problem: difficult to trigger but terrible consequences if you do.

    You are most likely to trigger a persistent slab in "prime time" avalanche terrain—slopes over about 35*—that has been loaded by the wind.  Keep in mind that these slides can be triggered remotely—from below, above, and to the sides of steeper terrain.

    (2/3/2021) This large slide likely occurred sometime Tuesday night (2/2) or Wednesday morning (2/3). It released on a 7,700' E-facing slope in Croy Canyon above Democrat Gulch.

Avalanche Discussion

A series of storms are stacking up in the Pacific and snowfall will arrive in the majority of the forecast area by noon today. The first storm will bring snow this afternoon and into Friday morning. The second storm will bring an additional pulse of moisture during the day on Saturday. For both systems, expect a heavy bias toward greater snow amounts near Banner Summit, the Sawtooths, and the western Smoky Mountains. 

Although the danger is likely to rise in the neighboring zones to the north, these storms will have little impact on the Soldier and Wood River Valley Zone. Potentially 5" of new snow will fall in the Soldiers and less than that in the Wood River Valley by Sunday morning. 

Despite that fact, avalanche conditions remain tricky. The recent extreme wind event formed hard slabs on many slopes. These slabs formed over a generally shallow, weak snowpack. Slabs that support the weight of skiers and sledders are notorious for producing avalanches that break wider or higher than expected. 

Regioni coperte