Boletín de aludes

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Peligro de aludes

Sun
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The snowpack can still produce dangerously large avalanches around 2 feet thick. Reduce your odds of triggering a slide by sticking to lower-angled terrain without steep slopes above you. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    Our area continues to be plagued by a layer of faceted snow—in this zone, it's buried beneath a dense 1.5-2' thick slab. Since it was first buried in December, we've recorded nearly 400 avalanches—the vast majority broke on this persistent weak layer. Around 20 of these were human-caused. To say this layer has a poor track record is a bit of an understatement.

    Two factors make this persistent slab problem particularly long-lasting: 1) The layer is especially "bad" since it formed during 3-4 weeks of perfect faceting conditions, and 2) It was slowly loaded over the course of a month by a series of small to medium storms. Now that we've gone more than a week without significant loading, we know the stability is improving—but it's difficult to say by how much. Reports of snowpack collapsing yesterday on Galena Summit and Horton Peak are signs that triggering an avalanche is most definitely still on the table.

    You can reduce your risk by avoiding slopes over about 35 degrees, especially those that have been affected by the wind. Pay attention to what's below you—look for trees, rocks, gullies, and other terrain traps. Given the possibility of remote-triggering slides, avoid terrain with steep slopes above you. 

    (1/19/2021) Large persistent slab avalanche that failed in the White Clouds around our last storm on January 13th.

Avalanche Discussion

FAQ's regarding the current avalanche conditions...

Q: Where are conditions most dangerous?A: The last storm produced the most widespread avalanche activity in the Galena Summit & E Mtns and Sawtooth & W Smokys zones, but natural avalanches occurred across the forecast. Where the slab thickness above the weak layer is around 2' seems to be the "sweet spot"—these are the areas where you are most likely to trigger a slide.

Q: Are there areas where conditions are less dangerous?A: In the Banner Summit zone, the weak layer is buried beneath a very dense,  3+' thick slab. This makes it more difficult for your weight to affect the weak layer, but if you were to trigger a slide, the consequences would be disastrous. The mountains above Hailey and Ketchum have received less snow this year, and instability is generally limited to where the wind had formed thicker drifts above the weak layer.

Q: Is it getting better?A: Yes. But the tougher question is by how much? With an especially bad persistent weak layer like this one, there are no clear indicators of when the risk of triggering an avalanche has decreased to an acceptable level. Some important clues include decreasing signs of instability such as collapsing and cracking and a prolonged period with no new loading from snowfall or wind. The consensus amongst local avalanche professionals is that we're not there yet.

Q: What should I do about it?A: Glad you threw me an easy one. With no clear answer about how much the snowpack has stabilized, we need to offset the uncertainty with a healthy margin of safety in our terrain choices. In simple terms, this means continuing to choose conservative, lower-angled terrain that isn't threatened by steep slopes from above.

Q: What happened this past week?A: Funny you should ask. Be sure to check out our latest Weekend Update where I attempt to answer just that.

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