Boletín de aludes

Soldier & Wood River Valley 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 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Large avalanches are unlikely. The highest chance of triggering large slides is on very steep, rocky slopes—especially where the snowpack is thinner (less than about 4 feet thick). 

Problemas de aludes

  • Persistent Slabs

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

    Triggering a persistent slab avalanche is unlikely but not impossible. Persistent weak layers (facets, facets and crusts, isolated surface hoar) exist throughout the snowpack on nearly all slopes. Know that they are under your feet or sled. Recent warm and dry conditions are giving these weak layers some time to rest, but they will not magically go away.

    You're most likely to find trouble on very steep (approaching 40 degrees), rocky, wind-affected slopes. Terrain like this is most common at upper elevations. Because these weak layers are deeply buried, any slide that initiates on them could be large and destructive.

    ADDITIONAL DISCUSSION: Calm, clear weather today could produce some small, sun-induced loose snow avalanches in very steep, rocky terrain, most likely on E-S-W aspects. Think about the consequences of being caught in even a small slide before committing to serious, exposed terrain.  If you are sinking into wet, sloppy snow this afternoon, find a colder slope to play on.

    There's still a small chance of triggering a persistent slab avalanche, primarily in terrain like shown in the photo—very steep, rocky, and wind-affected. Johnstone Peak area.

Avalanche Discussion

For now, the danger is LOW and it'll take pronounced warming or a decent storm to change that. However, this is by no means a year (or a shade of LOW danger) that warrants a free-for-all.  Scott's and Ben's Forecast Discussions over the past couple of days have tackled the nuance to LOW danger. Among other points, Ben touches on uncertainty and unpredictability and Scott nicely illustrates how all LOW danger is not created equal. If you have a minute, click those links and scroll down to the Forecast Discussion, it's well worth your time. 

I find making decisions appropriate for the conditions much easier when the danger is elevated. I have a low risk tolerance, particularly when the hazards are veiled in uncertainty, so sticking to safer terrain is an easy choice. This season, that uncertainty is primarily tied to weak snow layers buried deep in the snowpack. All recent evidence points toward improving stability, but a poor snowpack structure (strong snow over weak snow) remains. Even as the danger decreases I find this structure hard to ignore, particularly where the snowpack is less than about 4' deep.

Over the next 5 days we've got plenty of sun and slowly increasing temperatures to look forward to. Here are a few things to keep in mind as we head into the weekend:

  • Wet avalanches look like they have (so far) involved only recent snow, and have remained small. If overnight temperatures start to hover near freezing, we may see larger slides gouging deeper into the snowpack. This scenario will become more likely as we head into the weekend or early next week. 
  • We observed numerous cornice failures during last week's warmup. These huge chunks of snow are more prone to sagging and failing during warm weather. They can fail much further back on a ridge than you'd expect, so give them a wide berth. 
  • You're most likely to trigger a large, slab avalanche where thinner snow cover provides better access to buried weak layers. As a whole, the snowpack is thinner and these spots are more numerous in the alpine terrain of the Boulder, the White Cloud, and the Pioneer Mountains.

Don't let improving stability derail your safe travel practices. LOW danger can be a double-edged sword. The decreased likelihood of triggering a slide can lure us into more consequential terrain where even a small slide could be dangerous. If you see a wind-loaded slope or another indicator of potential instability, don't assume it's safe just because the danger is LOW.

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