Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
Auf der Karte ansehen

Lawinengefahr

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

Kernpunkte

You may be able to trigger avalanches large enough to bury a person at upper elevations and on some middle-elevation slopes facing W-N-E. You may or may not observe obvious warning signs like snowpack cracking or collapsing before triggering a slide.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    You could trigger 1-2 foot thick avalanches that fail on buried persistent weak layers near the base of the snowpack. Weak layers exist on upper elevation slopes and most middle elevation slopes facing W-N-E. You'll find a stack of weak, sugary facets on shadier slopes. On sunnier slopes, the weak layers present as a variable series of crusts and facets. 

    You're most likely to find trouble where the slab above the weak layer is strong. The strength of the slab will vary from slope to slope (video). You've found a strong slab if pushing your ski pole to the ground is difficult. A strong slab will also likely support your weight if you hop off your machine or step out of your skis.

    You may or may not observe obvious signs of instability, like cracking and collapsing of the snowpack. Tracks on a slope are not indicators of stability—avalanches may be triggered after many riders have crossed a slope. The best way to manage this problem is to avoid avalanche terrain where denser slabs rest above weak, older, facets and crusts. Short of that, you can reduce your risk by avoiding large avalanche paths, and those with ugly consequences if you are caught in a slide.

Avalanche Discussion

The odds that you trigger an avalanche are low but not zero. The last reported slab avalanches are estimated to have occurred over two weeks ago (database). While weak layers in our snowpack have marginally gained strength, the overall stability is improving as we've gone days without a significant storm. Many soft snow surfaces are out there, thanks only in part to the skiff to 2 inches of new snow. The prolonged drought has faceted the snowpack, even degrading what were once stiff, alpine drifts into soft, recycled powder.

On the plus side, this process has weakened the slab in some areas, limiting its ability to produce an avalanche. The downside is that strong snow over weak snow setups can be harder to identify, masked by weak snow at the surface. The difference between a slab strong enough to produce an avalanche and one that's not is not an assessment we should hang our hats on. Rather, let's look for stronger slabs and know that this is where we're more likely to find trouble. Generally speaking, stronger slabs will exist in areas with a thicker slab or in areas that are more commonly exposed to the wind.

As you head into the mountains, monitor the stiffness of the snow you're traveling through. The recipe for a persistent slab avalanche calls for a slab. This is the key ingredient as you climb into an environment with well-known and widespread weak layers. Areas that lack a slab can produce loose, dry facet-lanches. While less likely to bury you, these slides can easily knock you off your feet or carry you into unwanted terrain. 

Abgedeckte Regionen