Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Unfortunately, we can't rule out the possibility of triggering a large, destructive avalanche. You can greatly reduce your risk by steering clear of very steep, rocky, wind-affected slopes. In wind-sheltered terrain, use normal caution and continue to adhere to safe travel practices.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    While the rest of the area has dropped to LOW danger, we're not quite ready to take that leap of faith in this zone. The faceted snow that exists near the ground on NW-N-NE-E facing slopes remains especially weak, and the slab thickness (3-5') makes it more possible to impact it with our weight compared to the deeper snowpack areas to the north and west. While triggering this layer isn't that likely, it's more likely than in the rest of our area.

    Most local professionals and savvy backcountry riders are still leery of "prime-time" slopes (around 35-45 degrees) that are wind-affected and rocky. Triggering an avalanche on wind-sheltered slopes, or those with a more uniformly deep snowpack, is much less likely.

    ADDITIONAL DISCUSSIONIf your adventures take you into alpine terrain, it may be possible to trigger a wind slab—especially where these have formed on icy surfaces or sugary snow. These are likely to be small but could be dangerous in consequential terrain.

    This large, natural avalanche released naturally near the end of the last storm in very steep, rocky, wind-loaded upper elevation terrain in the 4th of July drainage in the White Cloud Mountains.  

Avalanche Discussion

THE "SCALE OF FORECASTER SURPRISE"Avalanche forecasters use defined guidelines for the various scales that describe avalanche danger, likelihood, size, etc. If you're either very curious or very bored, check out the Conceptual Model of Avalanche Hazard in your free time. These definitions are important and necessary, but there are often cases in the real world when these definitions are challenging to apply, and forecasters turn to less formal definitions that would never make it into a scholarly article. Ask Scott about his "pucker factor" scale sometime...

When discussing the danger for a forecast zone, we often find ourselves describing how "surprised" we'd be if someone were to trigger an avalanche. This has led me to formalize this into the Sawtooth Avalanche Center "Scale of Forecaster Surprise". It starts with a question: "Ethan and Ben, how surprised would you be if we heard that someone triggered a slide in the ______ zone?" They would carefully select from one of these options:

  1. Expected. You know that if people get into avalanche terrain, they will definitely trigger an avalanche. You'd be surprised if someone didn't trigger something.
  2. Unexpected. Stability has improved and you don't think someone would trigger a slide. But it wouldn't be a total surprise.
  3. Surprised. The snowpack is generally stable, but there are nagging doubts and uncertainty. You can conceive of a situation where someone might trigger a slide.
  4. Shocked. Conditions are stable, but a slab/weak layer structure still exists. If someone were to trigger a slide, you could at least explain how it might have happened.
  5. Inconceivable. The snowpack lacks the structure to even produce an avalanche. If you heard a slide was triggered, you'd doubt the report until you saw it for yourself.

Clearly this scale is heavily weighted towards the "unexpected" side—that's not by accident. It's when avalanche conditions are improving, and especially as persistent weak layers are becoming less problematic, that our traditional definitions seem to leave us hanging. Here's the surprise rating I would give to each zone:

Galena Summit & Eastern Mtns: Despite over a week with no loading, a well-defined slab/weak layer structure is showing little sign of change. Surprised. Soldier & Wood River Valley: The October weak layer is not as widespread, and this zone has received less recent loading. Shocked. The exception is near Dollarhide Summit, where conditions are more similar to GS & E (Surprised).Sawtooth & Western Smoky: The October weak layer is very deeply buried and is showing signs of being "squashed". Shocked.Banner Summit: Same as S & WS, but even more deeply buried and with less terrain having the necessary trigger points. Shocked+.

Be sure to check out Ethan's latest Weekend Update!

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