Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You may be able to trigger avalanches up to 18" thick, especially where the wind has formed drifts in recent days. Triggering large avalanches is possible but 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.

If you're traveling in the White Cloud Mountains, also refer to the Sawtooth & Western Smoky Mtns zone forecast. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    You're most likely to trigger large avalanches where stiffer wind-affected snow overlies weak, sugary, faceted snow or a series of crusts and sugary facets.  On Sunday, local professionals reported triggering multiple slab avalanches that failed on this weak snow (see photo at right). Sunday through Tuesday, winds blew at moderate to strong speeds and added additional weight to some slopes.  

    The weak faceted snow layers are widespread, but many slopes are lacking a thick, dense slab above the weak layer. Slopes that have less than about a foot of soft snow above the sugary facets are much less dangerous than those slopes with more snow or stiff, dense layers above the crumbly facets. You will find the thicker, stiffer slabs in drainages that have received more recent snowfall and in wind-loaded terrain. 

    Steer clear of steep slopes if you see cracks shooting out from your skis or sled, or if you feel the snowpack collapse or hear whumpfing noises. Persistent slab problems are difficult beasts to deal with. These types of avalanches may be triggered from gentler terrain 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.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    A fresh batch of wind slabs formed in the last couple of days. While these slabs should be relatively small and isolated, they could knock you off your feet or sled. In addition, these slabs are adding stress to the weak snow described above. An avalanche that starts as a small wind slab has the potential to step down to deeper weak layers buried in the snowpack, resulting in a large and dangerous avalanche.

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. 

Regioni coperte