Boletín de aludes

Banner Summit

Sawtooth Avalanche Center
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Peligro de aludes

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

Lo esencial

Conditions are generally stable and large avalanches are unlikely. On very steep slopes facing the sun, wet snow avalanches will become likely as the day heats up. Look for small, sensitive wind drifts in areas exposed to the wind. 

Problemas de aludes

  • Loose Wet

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

    A handful of natural wet loose avalanches released with yesterday's sunny skies and warming temperatures (photo above/right). With warmer temperatures last night and hotter weather on tap today, expect the likelihood of natural and triggered wet slides to increase this morning. As sunny slopes heat up, monitor the mushiness of the surface. Once the mush gets deeper than about 4-6", triggering a sizeable sluff of wet snow on slopes approaching 40 degrees will become likely. Plan to be off of steep, sunny slopes early in the day, and don't linger beneath terrain that is getting direct sunshine. 

    ADDITIONAL DISCUSSION:Thursday's spring storm produced a combination of new snow and wind, and numerous natural and triggered wind slabs were reported across the forecast area on Friday. I was out in the Banner Summit zone yesterday (observation) where I didn't find any problematic wind drifts but did see evidence of recent wind. Another party nearby triggered a small wind slab. Keep an eye out for these if your travels take you into steep upper elevation terrain. Being able to identify and avoid wind slabs is a critical backcountry skill—read more in the Forecast Discussion below. 

    (3/27/2021) Small wet loose avalanche down the ridge from Copper Mountain on Banner Summit. E, 8800'.

Avalanche Discussion

Wind slab problems are different in that they tend to be localized in the terrain. In contrast to a buried weak layer or a uniform blanket of new snowfall, wind slabs often occur in specific locations with (sometimes) identifiable boundaries. Being able to manage a wind slab problem is a critical backcountry skill—this is especially true for skiers and riders who seek out steeper terrain in alpine environments. While wind slabs can—and do—exist anywhere there is snow on the ground, their preferred habitat is the complex, wind-exposed, open terrain of the high mountains. Let's go over the identification, "evaluation", and avoidance of wind slabs.

IDENTIFICATIONIdentifying wind slabs does not involve getting out your shovel. You find them primarily by looking and feelingLook for changes in surface texture. Wind slabs often looked rippled or "chalky". Feel for differences in snow consistency. Drifted areas usually have a dense, punchy, or hollow feel. Snow that has visual effects from wind isn't always a wind slab, which is why a combination of looking and feeling is so important. This can take some experience, so be extra-cautious until you build your skills.

EVALUATIONI almost skipped adding this section because evaluating wind slabs can be a slippery slope (pun intended), and it's almost always best to skip straight to avoidance. The sensitivity of wind slabs can be tough to predict and often changes from location to location. Stomping or slope cutting a wind slab on a low-consequence slope can provide useful information, but not getting a result is no guarantee that the next loaded area won't provide a magic carpet ride. 

AVOIDANCEAs I alluded to above, once you've identified a wind slab, the best approach is usually to let sleeping dogs lie. Avalanche professionals rarely feel comfortable sliding or riding on a wind slab—even if there has been no sign of instability. If you're able to identify the perimeter of a wind slab, then you can navigate around it—giving it a wide berth and yourself a healthy margin of safety. If the boundaries of the wind slab aren't clear, then avoiding the slope entirely will be the best option.

Be sure to catch up on what happened this past week in Scott's Weekend Update!

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