Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Triggering a dangerous avalanche is likely. Skiers and riders triggered numerous avalanches over the past week—most from low-angle terrain a large distance from where the avalanche released. Avalanches will be larger and more destructive as you gain elevation and move into wind-affected terrain. Traveling safely even near avalanche terrain is difficult—build in extra safety margins.

Problemi valanghivi

  • Persistent Slabs

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

    Expect to trigger a 1-2 foot thick Persistent Slab avalanche in areas sheltered from the wind. As you climb into windier terrain you could trigger a slide up to 5 feet thick. These avalanches will break wide and may fail in unusual locations. Anticipate remotely triggering these avalanches a large distance away from where they release.

    We've observed dozens of Persistent Slab avalanches over the past week—many of which were human-triggered. Assume this problem exists on all upper and middle elevation slopes and shadier aspects at low elevations. Avalanches are failing on a variety of weak layers; surface hoar and/or facets on shaded slopes and a crust + facet combination on sunnier slopes. 

    The avalanches described above could "step down" to an additional weak layer of snow near the ground. This basal weak layer exists on upper elevation slopes and shaded middle elevation slopes. Avalanches that break down into this snow are likely to be unsurvivable (video).

    (1/19/2024) This photo shows several large avalanches that were remotely-triggered by riders in the Beaver Creek drainage. The furthest away slide is over 800 feet wide, and failed a half mile from where the avalanches were triggered, out of sight on the right side of the photo.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Ongoing light snowfall will keep the possibility of smaller avalanches on the table. Look for fresh cornices or small wind slabs in areas exposed to the wind. Loose snow avalanches are possible on slopes sheltered from the wind. These problems may be large enough to knock you off your feet or bury you in a terrain trap. More concerning is the possibility for these slides to trigger the Persistent Slabs described above.

Avalanche Discussion

Yesterday, I expected to trigger an avalanche. I mean, why not? Numerous, large human-triggered avalanches have been reported over the last week. The frequent collapsing of the snowpack is a reminder that January's storms stacked dense slabs atop an ugly weak layer. A weak layer that is uniquely widespread. A weak layer that's produced avalanches breaking thousands of feet wide. A weak layer that's enabled slides to pull back into relatively flat terrain above steeper slopes. Simply put, it's dangerous out there. 

What worries me most is that the skiing and riding are great! Small storms continue to roll through with minimal wind. Most snow surfaces are soft and inviting. Yesterday, I caught myself eyeing up a steeper exit than I'd planned. Snapping back from my brief lapse of powder-lust I reminded myself of the continual collapses, the ugly snowpack structure, and the unstable test scores—no thanks. Although small, the line I imagined traversed above creek beds and ended in a road cut. These not-so-obvious avalanche paths at lower and middle elevations are deceptively hazardous. Some specifics for this zone: 

WOOD RIVER VALLEY: The mountains around the Wood River Valley have received the short end of the snowfall stick this season. These hills remained almost completely brown during early-season storms, with snow beginning to accumulate in December. Today, you'll find 1-2 feet of snow on the ground on shaded slopes at middle and upper elevations. Despite the thin snowpack, many slopes now have a slab perched above weak snow near the ground (observation). 

DOLLARHIDE to the SOLDIERS: The western part of this zone has a much deeper snowpack, including at lower elevations. Dollarhide Summit has 4 feet of settled snow on the ground. Here, and west into the Soldiers, you'll find a snowpack that resembles that found in the Sawtooth & Western Smoky Mtns forecast zone. The snowpack extends to the valley bottoms, and the avalanche problems do too (observation).

Ongoing storms have not given our Persistent Slab problem a break. Enter the mountains with a conservative travel plan and stick to it. Be aware of people near, above, or below you;  accidentally triggering a large avalanche on another group is a real possibility.

 

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