Lawinenlagebericht

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 7 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Triggering an avalanche on weak layers buried 1-3 feet deep is becoming less likely. You can reduce most of the risk of triggering a slide by avoiding slopes where the wind has formed drifts or stiffened the snow surface. This will be most common at upper elevations, but you may also find wind-affected slopes in exposed, middle elevation terrain.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2

    This zone has persistent weak layers buried 1-3 feet deep on many middle and upper elevation slopes. People often ask how these weak layers heal. There's no magical formula, but the most important factor is time. It's been a week or more since the snowpack has been significantly stressed by new snow, wind, or warming temperatures. Imagine how you'd feel after a week on the beach with no email, no texts, and no news. Given a week of relaxation, both you and the snowpack will feel better—but that doesn't mean your problems have miraculously disappeared forever.

    As the likelihood of triggering an avalanche continues to decrease, it's important to understand where the chances remain the greatest. You can reduce most of the risk of triggering a slide by avoiding terrain with these characteristics:

    • Wind-loaded terrain: Slopes where recent or past wind formed drifts and/or stiffened the snow surface.  This is especially true in the Wood River Valley, where many wind-sheltered slopes are turning into full-depth sugary snow.
    • Steeper slopes:  "Prime-time" avalanche terrain around 35-45 degrees in steepness.
    • Southerly facing terrain:  In the Soldiers where there is more consistent snow coverage on sunny slopes, crusts and facets 1-3 feet deep seem to be stabilizing more slowly than the weak layers on shadier slopes.

    ADDITIONAL DISCUSSIONIn some upper elevation locations, yesterday's 1-2 inches of new snow was getting transported by gusty W to NW winds (see video). You may find thin, sensitive wind slabs (like these) today along higher ridgelines.

Avalanche Discussion

When I was younger and less experienced, the question I often asked before committing to avalanche terrain was, "Do I think this is going to slide?" If I thought the answer was no, I went for it. This left little margin for error since the question of whether or not a slope is going to slide is a tough one to accurately answer. And it turned out I answered this question wrong a few times.

Eventually, my approach changed. One job hazard of being an avalanche forecaster is that with time, you see a lot of weird things that surprise you. I've realized that answering the question I used to ask just isn't possible with an acceptable level of certainty. So I started asking a different question before riding steep terrain: "Would I be totally surprised if this thing avalanched?" The difference between these questions is subtle but important. The second question is more conservative and takes into account the uncertainty faced when dealing with a tricky snowpack—which is what we have now.

So do I think someone will trigger a slide today? No. But would I be totally surprised if someone does? When an obvious persistent weak layer is present—like it is throughout our forecast area—the answer to this question is also No. This is especially true for someone riding in the type of terrain described in the Problem Discussion above: wind-affected, prime-time slope angles in our southern and eastern mountains; and rocky, "alpine-y" slopes with variable snow depth in our northern and western zones.

One important outcome from this approach is that as time has passed and my avalanche knowledge has increased, I've ridden less steep terrain—not more. But when I do get into steep terrain, I enjoy it more knowing that I am more confident in my decision and that I'm exposing myself to less risk.

The incident report for the January 15th avalanche fatality in Baker Creek will be published later today or tomorrow.

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