Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Fri
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 a slab avalanche is not likely, but the resulting slide will be 1-3 feet thick and involve the majority of the winter’s snowpack. These avalanches are most likely where the wind has formed drifts or stiffened the snow surface. To reduce your risk, stick to lower angle terrain and avoid obviously wind-loaded slopes.

Lawinenprobleme

  • Persistent Slabs

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

    Buried weak layers of facets and depth hoar sit near the base of the snowpack. These layers were responsible for the last slab avalanches reported in this zone (see photo) and remain our greatest concern. Triggering an avalanche on one of these layers is unlikely but the resulting slide will be massive. 

    Here are some considerations to help you reduce your risk:

    • Recent wind-loading: Slopes with stiff or hard layers somewhere above the weak layer are more suspect than slopes where you can easily get your arm, ski pole, or sled down to or near the ground.
    • Slope angle: Avalanches are most likely in "prime time" avalanche terrain, slopes around 35-45 degrees in steepness. However, remember that persistent slab avalanches can be triggered remotely–from gentler terrain below or to the sides of steeper slopes.
    • Aspect: Last week’s avalanche activity was focused on slopes where the sun had formed crusts.

    Additional Discussion:Be on the lookout for small wind slabs in exposed terrain particularly in areas with greater recent snowfall like the Smoky Mountain Crest. If the clouds hold off until later than forecast, loose snow avalanches are a possibility again this afternoon. These slides are most likely on sheltered SE-S-SW-W facing slopes while they directly face the sun.

Avalanche Discussion

Persistent slab avalanches remain our primary concern. Weak layers comprised of facets, crusts, and depth hoar exist across the whole of our forecast area. These layers are responsible for the vast majority of the avalanches we’ve seen this season. One primary factor that changes from range-to-range is snowpack depth. 

In our northern zones, these weak layers are buried 3-6’ deep. An overall deeper snowpack has fewer thin spots and thus provides less opportunity for a skier or rider to affect the weak layers near the ground. In our southern zones, the snowpack is shallower, providing more potential trigger points. 

So why is the danger the same across all zones? The avalanche danger is a balance of the likelihood of triggering a slide and the size of the resulting avalanche. So while you’re more likely to affect the weak layers near the ground in a shallower snowpack, the resulting slides will be smaller. I carefully chose the word “smaller” and not “small” because a 1-3’ thick persistent slab avalanche is plenty big to ruin your season–or worse.

Unless you buy a plane ticket to the Cascades, there's no way to completely avoid the widespread persistent weak layers near the ground. So what can you do? Over the last several days, we’ve been listing ways to reduce your risk. Write those key points down or screenshot the forecast and take it with you. Does the terrain you're considering share one or more of those characteristics?

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