Lawinenlagebericht

Soldier & Wood River Valley 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 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

You may be able to trigger avalanches where the wind has formed dense drifts in recent days. Triggering large avalanches is much less likely in sheltered terrain where the snowpack is thinner and softer. Avalanches may be triggered from gentle terrain below, above, and to the sides of steep slopes.

Lawinenprobleme

  • Persistent Slabs

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

    You're most likely to trigger large avalanches where stiffer wind-blown snow overlies a stack of weak, sugary, faceted snow or a series of crusts and sugary facets.  On Sunday, local professionals reported triggering slab avalanches that failed on this weak snow in the mountains just north of this zone (see photo at right). 

    Sunday through Tuesday, winds blew at moderate to extreme speeds, forming some hard slabs on isolated slopes. The combination of fresh hard slabs and weak faceted snow is a perfect recipe for an avalanche. The weak faceted snow exists on most slopes, but the hard slabs are not widespread. 

    If you find yourself in exposed terrain and the snowpack is hard and hollow-sounding, be careful. Hard slabs can break above you in relatively gentle terrain, and these types of avalanches may be triggered from below. above, and to the sides of steep slopes. 

    (12/20/2020) This avalanche was remotely triggered by local professionals on Sunday. It failed on the layer of weak snow that exists across our forecast zones. Based on the appearance of the crown, it appears that wind had loaded this slope.

Avalanche Discussion

Weird Weather Makes Weird Avalanches

As avalanche forecasters, we spend a lot of time thinking about uncertainty and confidence. Thinking about these things helps us to produce forecasts that are both accurate and useful for you as a reader (at least, that's the idea). On days when we have a lot of information about the snowpack and the weather is simple, we can have high confidence in how the snow will behave. When the weather is changing rapidly and we find ourselves dealing with snowpacks that are unusual, our uncertainty can be high. This is the latter. 

There is no reason to hide the fact that we have a lot of unknowns and a lot of unknowables throughout the forecast area. The widespread layer of weak, faceted snow buried in our snowpack is quite unusual, a once in a decade or two sort of thing. The warm, wet weather that we just experienced is also quite unusual for this time of year; Stanley set the record for the highest temperature seen on the solstice, breaking a record that was set over 50 years ago. Now, it's near zero degrees F and there's a little "blower powder" window-dressing on top of the snowpack. The combination of unusual weather and snowpack events basically puts us in uncharted waters. The first step in dealing with uncertainty is to acknowledge its existence.

As our abnormally weak snowpack slowly adjusts to the recent load, remember that weird weather makes weird avalanches. I'll be traveling cautiously today, building some extra safety margin into my program. 

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