Boletín de aludes

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Peligro de aludes

Mon
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Avoid steep slopes with wind drifts or stiff snow on the surface to reduce the chances of triggering an avalanche. Although not likely, triggering a large, destructive avalanche breaking deeper in the snowpack remains a possibility. Safer conditions—and the best skiing and riding—can be found on gentler slopes sheltered from the wind.

Conditions are more dangerous near the Smoky Mountain crest/Dollarhide Summit where the recent storm hit the hardest. Refer to the Galena Summit & Eastern Mtns Forecast if you're traveling in this area.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Last week's storm dropped 12-30" of new snow in this zone, accompanied by strong winds. The greatest amounts fell from Dollarhide Summit SW towards the Soldiers. Despite lower snow totals around the Wood River Valley, small, natural, and skier-triggered avalanches were reported this past week, and a fresh natural wind slab was reported yesterday (photo above/right). Wind slabs will be most common at upper elevations, but this week's wind also drifted some open middle and lower elevation terrain (example).

    Even though the storm has ended, wind-loaded terrain presents two lingering problems. The first is that while wind slabs are becoming less sensitive, there are likely a few out there that you could still trigger. The second problem is that wind-affected slopes have more recent loading and a stiffer slab sitting atop buried weak layers (see Additional Discussion below and Problem #2).

    If someone were to trigger a slide today, it would most likely occur in wind-loaded terrain. For that reason, the best approach will be to avoid steep slopes where you find evidence of wind loading such as drifted, pillowed areas,  or feel denser/stiffer snow beneath your board(s) or sled.

    ADDITIONAL DISCUSSIONIn other zones, yesterday's pattern of natural avalanche activity points to a probable crust/facet layer on steep (>35 degrees) slopes that face SE-S-SW. Notable slides on sunny aspects include Galena Peak (photo),  behind Horton Peak in Pole Creek (photo), and in the Western Smokys (photo). Soldier Cat Ski Guides noted poor test scores on sunny slopes that may indicate this pattern extends to that area as well. Until we have better information on this weak layer, most of us will be avoiding steep, southerly-facing slopes—especially those affected by the wind.

    (1/8/2022) Small natural wind slab avalanche in Croy Canyon. 6800’, E. Photo: V. Rossin

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    Weak October snow is buried 2-5+' deep on most shady middle and upper elevation slopes. Some sunnier, upper elevation aspects have this layer too. The recent storm event just added a huge load to this weak layer, especially on wind-loaded slopes. It'll be the most deeply buried near Dollarhide Summit SW to the Soldiers, and has been less problematic in the Wood River Valley.

    Yesterday's observations in neighboring zones revealed surprisingly few avalanches breaking deep into the October snow (although see photo above/right), which offers some hope for a future where we're less concerned about this layer. But I don't think we're quite there yet. Where are you more likely to trigger an avalanche on this layer? Most savvy backcountry skiers and riders are still avoiding very steep (>35 degrees), rocky, wind-affected slopes at upper elevations and in alpine terrain.

    (1/8/2022) Natural avalanche near Titus Ridge in the Galena Summit 7 Eastern Mtns zone. Judging by the depth, it looks to have failed on weak October snow near the ground. 9400', N. Photo: T. Haskins

Avalanche Discussion

A BRAVE NEW WORLDLast week's multi-day storm cycle dropped 12-50" of new snow across our area, with the Western Smokys, Smoky Crest, Sawtooths, and Banner hit the hardest. Although this storm didn't change the game as much in the Wood River Valley where less snow fell, many other portions of the forecast area are dramatically different. It's time to take stock and make sense of this new world. Yesterday's clearing skies gave us a first glimpse at the pattern of avalanche activity, but we look forward to more "boots on the ground" observations in the coming days. Let's consider what we do and don't know.

Observations so far (knowns):

  • Numerous storm/wind-related avalanches occurred—not surprisingly given the massive snowfall, intense precip rates, and strong winds. 
  • Enough avalanches occurred on southerly aspects (Galena Peak, Boulders, Pole Creek, Western Smokys) to conclude a pattern exists. These slides likely failed on a crust/facet layer that was the old snow surface prior to the storm.
  • Few observed avalanches broke on the deeper October snow—at least from what we've seen so far. But here's a photo of one that did near Titus Ridge.

Observations needed (unknowns):

  • Is the crust/facet layer on steep, sunny slopes still sensitive or has it "done its thing"?
  • Will additional observations of avalanche activity show more slides that broke in October snow or reveal new patterns?
  • How deeply is the October snow buried? Where is it still a concern?

Until we get a better handle on our brave new world and the "knowns" list is longer than the "unknowns", most of us will be sticking to conservative terrain and embracing a wait-and-see attitude.

Be sure to catch up on last week's conditions in Chris' latest Weekend Update.

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