Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 6 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Conditions are not straightforward. Triggering a large avalanche is possible where weak snow lingers under a cohesive slab. You may or may not see obvious signs of instability before triggering a slide. Avalanches can be triggered remotely—from flat terrain below, above, and to the sides of steep slopes.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–2.5

    Weak snow sits underneath 1 to 4 ft slabs of consolidated snow on many slopes. These overlying slabs are thickest, stiffest, and most widespread in middle and upper-elevation winded terrain, and yet most sheltered slopes also harbor softer cohesive slabs resting over weaker snow. There are various buried weak layers, including sugary facets, surface hoar, and crust + facet combinations, that are most easily identified by digging into the snow. These are primarily found on NW-N-NE-E aspects, though they also exist, more variably, on the margins of sunnier aspects.

    Avoiding avalanche terrain where you suspect these weak layers to be lingering under the surface, especially in wind-affected areas, is the best way to stack the odds in your favor. Determining whether a given slope is safe to ride or just waiting for a trigger—you— is challenging. Due to the variable distribution and character of both the slabs and weak layers, stability can change quickly over short distances. Recognize that these avalanches may be triggered remotely - from above, below, and to the sides. You may or may not observe clear signs of unstable conditions, such as snowpack cracking and collapsing, before triggering a slide.

Avalanche Discussion

Over 100 avalanches (natural and remotely triggered) released last Wednesday-Friday. This diagram shows the spatial pattern of recent avalanche activity. Many recent avalanches were hundreds of feet wide, pulled into gentle terrain, and/or were remotely triggered - classic characteristics of persistent slab avalanches. Despite a lack of avalanche activity and diminishing reports of obvious signs of instability over the past couple of days, the weak layers responsible for all these avalanches will take a while to heal. Uncertainty with both their declining reactivity/triggerability and specific distribution are great reasons to build larger margins and multiple options into your mountain plans (great example here).

We're moving towards a low-likelihood-high-consequence situation with our given snowpack structure - in other words, SPOOKY. Identifying the ready-to-rip slopes (for either riding or avalanching) is becoming more challenging as the feedback from the snowpack becomes less frequent or obvious. At the same time, the consequences of being caught in an avalanche remain the same: these are expected to be large slides that could easily bury a person. Today's dusting of snow will only continue to muffle the obvious signs of instability you might find in the mountains while doing little to change the underlying problem. Think about the consequences of triggering an avalanche before committing to riding or skiing steep slopes, and when in doubt... mellow out.

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