Boletín de aludes

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Peligro de aludes

Thu
Alta montaña
2 · Moderado
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

Watch for wind drifts near ridgelines in upper elevation and alpine terrain. If today is sunnier than forecast, small, natural wet loose avalanches are possible.

Problemas de aludes

  • Wind Slabs

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

    The light winds and 3-6" of snowfall in the past 24 hours did not change the avalanche equation dramatically, but you're likely to find some fresh, soft slabs in alpine and exposed upper elevation terrain. Yesterday, SAC staff were able to get fresh drifts to crack just east of this zone near Galena Summit. Today, variable winds and light snow showers could continue building the drifts. The wind slabs should be most sensitive to triggering in "prime time" avalanche terrain, slopes about 38-45 degrees in steepness.

    Look for evidence of wind drifting such as smooth pillows of snow, dune-like drifts, ripples on the snow surface, and fresh cornices along ridgelines. Also, steep slopes below large cliff faces in the Sawtooth Mtns may have collected "spindrift", forming slabs on aprons lower in cirques. Cracks shooting out from your skis or board are a sure sign that you've found a sensitive wind drift. If the snow suddenly gets stiffer as you're moving on a steep slope, it's time to pay close attention and evaluate your terrain choices.

    Additional Discussion:  If the clouds part and the sun shines obstructed today, small, natural wet loose avalanches that involve the past few days' snowfall will become possible. Watch for fresh rollerballs on the surface. If you can easily make a snowball that would hurt your partner when you beaned them, then it's time to minimize your time in or below large, steep, rocky avalanche paths to avoid getting smacked by naturally-releasing sluffs. 

Avalanche Discussion

The avalanche danger scale is a five-step scale that avalanche forecasters use to communicate information about the avalanche hazards you might encounter in the backcountry. Of course, the world doesn't fit neatly into five boxes. There are innumerable shades of gray and subtleties that our simple scale glosses over.  Today, the avalanche danger at upper elevations is mostly MODERATE; however, the type of slide that you might trigger varies significantly over space. Some details:

  • Pioneer Mountains and Little Wood drainage: The southeastern corner of our forecast area got clipped by a significant stream of water since this weekend. While many of our other zones and areas picked up 4-12" of snow, this area is approaching 20" of snow and 2" of SWE (snow water equivalent). This relatively large, rapid load stressed a very weak snowpack for the first time this season; numerous large, natural persistent slab avalanches occurred. These types of slides can be triggered remotely, including from flat ground below avalanche paths—spooky! Dealing with this problem involves building wide safety margins into your travel plans.
  • Sawtooth, Smoky, White Cloud, and Boulder Mountains: 4-12 inches of snow fell in the past few days, and a couple more may fall today. Light to moderate winds built small slabs in some upper elevation terrain. 
  • All areas where more than about 6" fell yesterday: If the clouds part more than weather models predict, we will see natural wet loose avalanches involving the surface snow. I don't expect these slides—if they happen at all—to be large, but they could push you around or carry you into places you don't want to be. If it's warm and sunny, pay attention to your surroundings and what's above you. 

What tools or travel techniques will you use to manage these problems? The "simple" wind slab and wet loose problems present hazards that are predictable and easily avoidable. If you choose to enter avalanche terrain with this type of problem, you know what to look for and avoid. However, a persistent slab problem is an entirely different beast; you need to "close" large chunks of terrain to effectively manage this problem.

For all of the avalanche types or problems on today's menu, natural and/or human-triggered avalanches are possible—the kicker is the way you deal with the various problems is very different.

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