Boletín de aludes

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You could trigger a large, 1-2 foot thick avalanche. These slides are more likely in wind-drifted terrain and in the snowier, portions of this zone to the west of the Wood River Valley. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes.

Problemas de aludes

  • Persistent Slabs

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

    Wednesday west of Ketchum, Ben and I observed natural avalanches that occurred during last week's storm. As with the vast majority of the reported slides this season, they likely failed on a weak layer of facets buried in mid-December.

    Snowfall in this zone has heavily favored the Soldiers and the Smoky Mountain Crest near the head of Warm Springs. In these areas, the weak facet layer is capped with a dense slab on many slopes—a recipe that's proven dangerous time and time again. Closer to the Wood River Valley, this slab is less common and more closely tied to areas with wind-drifted snow. 

    Although we're several days out from receiving snowfall, this problem won't go quietly. The exceptional nature of this weak layer keeps the odds of triggering a slab avalanche elevated for several days following a storm. 

    The best way to reduce your risk is by sticking to lower-angled terrain and steering clear of slopes with runout zones that have trees, rocks, or terrain traps. Given the possibility of remote-triggering slides, avoid slopes directly beneath avalanche start zones. 

Avalanche Discussion

Just about everywhere we look we see avalanches that failed during our last storm. In the last few days, we've observed avalanches in the southern tip of the Smokys (in the Soldier and Wood River Valley Zone) and in 4th of July Creek in the White Clouds.

In all corners of the forecast area (that hold enough snow), it's the same story; weak facets buried in mid-December.  The variable, and what's at the root of different problems and danger levels between zones is the thickness of the slab.

Banner Summit "Low Probability, High Consequence"This zone has the deepest snow. The Banner Summit Snotel station shows a snow depth of 4' at just 7,100' of elevation. In this area, the December facets are buried under 3' of heavy snow. The dense slab is "protecting" the weak layer, making it more difficult for skiers and riders to trigger slides. However, the outcome of triggering one of these beasts is grim at best. 

Sawtooths & Western Smoky Mountains, Galena Summit & Eastern Mountains "The Sweet Spot"With less snowfall than Banner Summit, these two zones have a snowpack structure that remains ripe for human-triggered avalanches. The slab over the December facets is about 1.5-3' thick. Thin enough in many areas to be likely to trigger, but thick enough to produce large and dangerous avalanches. 

Soldier & Wood River Valley Mountains "A Fine Line"This zone shows large variability in snow cover and problem distribution. Snow depth in the Soldiers sits at about 3', Dollarhide Summit in the Smokys is pushing 4', and Baldy along with many of the mountainous areas to the east of the Wood River Valley hover around 2'. This video from Croy Canyon on Tuesday shows a weak but generally stable snowpack that lacks a slab. Contrast that with this video of a healthier slab, poor snowpack structure, and unstable snowpack test scores from near Dollarhide Summit yesterday. 

Wherever you travel, it's important to keep the big picture in mind. At any location where you're finding snow deep enough to ride or ski, you'll find a slightly different flavor of this same problem. The most effective way to deal with this poor snowpack structure is to stick to lower angled, low consequence terrain. Before committing to a slope, look for terrain traps like cliffs, trees, and gullies that will increase the consequences of being caught. Don't let your guard down. This uniquely well-developed and widespread weak layer should be at the front of your mind.  

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