Boletín de aludes

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Peligro de aludes

Fri
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
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

Sizable avalanches are unlikely, and most slopes are safe. Watch for isolated wind drifts at upper elevations. Very steep slopes that directly face the sun could produce small, natural loose snow avalanches (sluffs).

In the White Cloud Mtns, triggering a large avalanche on weak snow near the ground remains a possibility on very steep, rocky, wind-affected slopes. 

Problemas de aludes

  • Persistent Slabs

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

    Early-season persistent weak layers (facets and depth hoar) in the lower snowpack are widespread throughout the Galena Summit & Eastern Mtns zone. Given the lack of snowfall in recent weeks, most slopes are now stable. But, triggering a large avalanche on these deeply buried layers could result in severe consequences.

    The White Cloud Mtns are the proverbial "elephant in the room"; the snowpack there (video to right) remains spooky enough that none of the SAC staff is willing to venture into very steep, rocky, alpine terrain. As you travel south into the Boulder and then the Pioneer Mountains, the slab thins because less snow has fallen, decreasing both the expected size and likelihood of triggering avalanches.

    Slopes that we continue to avoid share the following characteristics:

    • Steep: Slopes in prime-time avalanche terrain around 35-45 degrees.
    • Wind-affected: Heavily wind-loaded by past wind events.
    • Alpine flavor: Complex terrain with scree piles, rocky ribs, and cliff bands help to create thin snow cover where weak layers are closer to the surface.

    ADDITIONAL DISCUSSIONLast weekend's wind and snowfall formed small drifts and slabs at upper elevations. Tuesday in the Sawtooth Mountains near the head of Beaver Creek, a skier triggered a small slab avalanche just below a corniced ridgeline. These small slabs may remain sensitive today, particularly where they overlie facets associated with a crust. 

    Yesterday, I observed a few small sun-induced loose snow avalanches. These small sluffs are possible again today, beginning on E-SE aspects in the morning, shifting to S-facing slopes during the day, and moving over to SW-W aspects in the afternoon. Pay attention to what's above you. These slides are most likely in very steep, rocky terrain sheltered from the wind.

Avalanche Discussion

Yesterday we dropped the avalanche danger to LOW for the first time this season. Really, this could have occurred sooner if it were not for the weak snowpack structure and continued small storms in the White Clouds. During a SAC forecaster conference call Tuesday night, we unanimously agreed this is the one area we’re not yet interested in skiing or riding steep, rocky, upper elevation terrain. If we were hunting for the rogue avalanche large enough to bury people, that is where we’d go.

Our hesitation stems from a layer of weak facets and depth hoar near the base of the snowpack. Atop this weak layer rests a spooky, stiff, midpack slab. This combination produced one of the most recent large avalanches in our forecast area. Triggering a large, full depth avalanche is unlikely but I'm not willing to bet my life on it. I'll continue to avoid windswept, rocky, alpine locations where the snowpack is thin. 

Overall stability improves as you head south in this zone. The last significant avalanches in the Galena Pass area and the Boulder Mountains occurred during extreme wind in early February. Even further south, the snowpack in the Pioneers is well below average. Over the weekend, Ben found a thin, weak, generally stable snowpack. 

There are lots of generally safe places to enjoy the day but a winter mountain environment is never devoid of avalanche danger. Continue to practice safe travel techniques: give cornices a wide berth, ski or ride one at a time, and keep an eye on each other. If you find a small sensitive slab, don't write it off as an "outlier". If something doesn't feel right, back off and come back another day. The consequences of even a small slide are amplified in extreme terrain. 

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