Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

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

In sintesi

A steady stream of new and windblown snow is creating sensitive wind drifts and loading buried weak layers—especially in the western portion of this zone (Dollarhide Summit to the Soldier Mountains). Triggering an avalanche 1-3 feet deep is possible, especially on steep, upper elevation slopes. You can dramatically reduce your risk of getting caught in an avalanche by sticking to wind-sheltered, mid-elevation terrain.

Problemi valanghivi

  • Persistent Slabs

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

    Early-season facets buried beneath a 2-3' thick slab are the top concern in this zone, but we can't rule out more recently formed weak layers (facets, isolated surface hoar, and crusts) in the top 2' of the snowpack. Slow but nearly constant loading from light snowfall and wind over the past 10 days—especially in the western portion of this zone—are not giving these weak layers any relief.

    Despite an overall lower likelihood of triggering a slide, persistent slab avalanches are unpredictable on the best of days. If you find one of the land mines out there—and believe me, they exist—the MODERATE danger rating will mean little to you. Given the uncertainty surrounding these weak layers, skiing or riding in "prime-time", consequential avalanche terrain is a risky business.

    You are more likely to trigger an avalanche on upper elevation, wind-affected slopes steeper than about 35 degrees. Triggering a wind slab (see Problem #2 below) could step down into these persistent weak layers, resulting in a much larger avalanche. Long story short, you can greatly reduce your risk of triggering a large persistent slab avalanche (or a wind slab avalanche for that matter) by sticking to wind-sheltered, mid-elevation slopes.

    (2/12/2021) This avalanche was triggered by a rider NE of Wells Summit in the Soldier & Wood River Valley zone. The slide broke around 40' wide and carried the rider about 100 yards. A section of the cornice also released in the slide.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Over the past week, the western portion of this zone—near Dollarhide Summit and the Soldier Mountains—have received a slow but constant trickle of snowfall accompanied by light to moderate winds, and this pattern continued yesterday and overnight. The low-density nature of the recent snow has made it easily transported by even light breezes. Almost all open or sparsely treed, upper elevation slopes have experienced at least some amount of wind loading over the past week.

    With a shift in wind direction to the NW yesterday, speeds increased into the moderate to strong range and formed a new round of wind slabs. Soldier Mountain Cat Ski guides remotely-triggered a wind slab avalanche that broke 1.5' deep (photo above/right). The wind continued to blow overnight and triggering an avalanche such as this one will remain possible today. Wind slabs may be found near ridgelines or mid-slope in exposed terrain. You're more likely to trigger a persistent slab avalanche (Problem #1 above) on wind-loaded slopes, and a triggered wind slab could also step down to these deeper layers. 

    (2/20/2021) Ski guides remotely-triggered this wind slab avalanche yesterday on Peak 2 in the Soldiers while doing mitigation work. It broke 1.5' deep. Photo courtesy Soldier Mountain Cat Ski.

Avalanche Discussion

We are saddened to report that an avalanche fatality occurred Friday in Smiley Creek in the Western Smokys Mtns (7 miles S of Smiley Creek Lodge, 8 miles SW of Galena Summit). A group of visiting snowmobilers was riding near the head of the drainage. A portion of the group was playing on lower-angled terrain above the Smiley Creek Road when one rider broke off from the group and ascended an adjacent slope. While climbing the slope, he triggered a very large avalanche that broke 3-4' deep and over 500' wide. The rider was caught and carried by the avalanche. He deployed his airbag and was found on the surface by his partners, but had succumbed to the injuries he incurred during the slide.

The avalanche occurred on a south-facing slope at 9,100' and ran 1,000' vertically. The debris ran into a well-defined gully where it piled up to an estimated depth of 20-30'. The slope angle of the start zone was an estimated 35-40 degrees. The top portion of the avalanche path was wind-loaded, and this area has received nearly constant light snowfall over the past week. The avalanche fractured on a thin layer of faceted snow atop a slick crust that was buried by the late-January storm. In a crown profile lower in the avalanche path, we found this layer to be buried over 3' deep—the top 2' of the snowpack consisted of newer snow from the past week.

We performed a site investigation Friday afternoon—watch the video. More details—including avalanche specifics, a map, and additional photos—can be found here. We extend our sincere condolences to the friends and family of the victim and greatly appreciate their willingness to talk to us about the event. A full accident report will be published in the coming days.

Another avalanche fatality occurred in southeast Idaho yesterday. Some preliminary details can be found in this news report. Information about all U.S. avalanche accidents can be found on Avalanche.org.

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