Lawinenlagebericht

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Lawinengefahr

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

Kernpunkte

Triggering a 1-3 foot thick avalanche is most likely on slopes with wind-drifted and stiffened snow at the surface. Slides are less likely but still possible on slopes sheltered from the wind. Avalanches may be triggered remotely—from flat terrain below, above, and to the sides of steep slopes.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2.5

    Above ~7,500 feet, slabs of last weekend’s snowfall exist up to 3 feet thick, sitting on top of weaker snow. You can find these persistent slabs on all aspects due to the widespread nature of the weak layers. 

    Observers continue to report collapsing, shooting cracks, and unstable test results. These are clear indicators of weak snow buried below the surface. These persistent slabs pose the most hazard in locations where the snow surface has been stiffened by wind or consolidated by recent warm temperatures. Slabs will feel firm under your feet or sled and can take the form of wind “drifts,” “whales,” or “dunes.”

    Sticking to lower-angled slopes will help minimize the chance of triggering an avalanche. Persistent slab avalanches can release in surprising ways, so keep a close eye on your partners and consider adding in a margin for error with the possibility of remote triggering a slide or an avalanche breaking wider than expected.

    (12/15/2024) This large, natural avalanche released last weekend in wind-loaded terrain in the Beaver Ck drainage in the western Smoky Mtns. E aspect near 10000'. Photo: Ben VandenBos

Avalanche Discussion

There are a wide variety of conditions seen in the gradients of snow from north to south and east to west across our forecast region. Despite this, the problem each of these zones faces is relatively similar. We can simplify it to: Last weekend’s storm snow is not bonding well to old snow that sat out and weakened for the couple of weeks after Thanksgiving... and there is weak snow at the bottom of the snowpack in most locations. Whether the interface involves crusts, facets, crust-facet-combos, deeply buried facets or surface hoar - they’re all very weak snow that hasn’t been thoroughly tested yet. Unfortunately, these weak layers probably won’t be proven innocent for a while, given how relatively weak and widespread these layers are.

So what is there to do while we patiently wait for the problem to heal? K-I-S-S (Keep It Simple Stupid). This pneumonic can easily be employed with your choices for simple terrain with low consequences, and by refreshing (and applying) your slope angle measuring skills to help minimize your exposure.  You can drastically reduce your risk of triggering a large avalanche by looking for and avoiding areas with a stiff slab near the snow's surface. Actively seeking out softer snow is safer and more enjoyable, but doesn't completely eliminate your risk. Given the sensitive weak layers we're dealing with, even deceptively soft slabs have the potential to release in steep terrain. The consequence of these smaller slides increases on slopes with terrain traps like gullies, cliffs, or thick trees. 

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