Boletín de aludes

Galena Summit & Eastern Mtns

Publicado el Dec 31, 2024válido hasta el Jan 1, 2025Sawtooth Avalanche Center

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Peligro de aludes

Wed

Alta montaña

3 · Notable

Límite del bosque

3 · Notable

Bajo el límite

2 · Moderado

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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Large avalanches, 1-4 feet thick, are most likely to be triggered in areas where wind has formed drifts or stiffened the snow surface. In areas sheltered from the wind, avalanches are less likely, but they’re still possible. You could trigger avalanches remotely—from flat terrain below, above, and to the sides of steep slopes.

Problemas de aludes

Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Alta montaña
Límite del bosque
Bajo el límite del bosque
Probabilidad
Likely
Tamaño
1.5–3
What and where is it: You could trigger 1.5-4 foot thick slabs, especially where wind formed drifts or stiffened the snow surface. Triggering an avalanche is less likely—but not out of the question—on steep slopes that are completely sheltered from the wind. The slabs rest above a variety of weak layers (facets, surface hoar, crusts, and combinations). The widespread nature of these weak layers means avalanches are possible on many aspects.

How can you recognize it: Snowpack cracking, and collapsing or whumpfing, are clear signs of unstable conditions. Watch for snow pillows, dunes, and ripples, and feel for stiff snow under your feet or sled. These are signs the wind has been at work transporting snow. Persistent Slabs won't always present with obvious signs of instability, assume the weak layers exist on most slopes.

How can you manage it: By avoiding steep, wind-loaded slopes, you can significantly reduce your chances of triggering an avalanche. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered. Remotely triggering an avalanche from flat terrain near steep slopes is a real possibility. Keep a close eye on your partner and the terrain that's above you. Manage your group by riding or crossing steep slopes one at a time, and avoid areas where terrain features like gullies, cliffs, or dense trees could increase the consequences of even a small slide.
(12/29/2024)

Skiers remotely triggered this avalanche on a NW facing slope near Avalanche Peak.
Wind Slabs
N
NE
E
SE
S
SW
W
NW
Alta montaña
Límite del bosque
Bajo el límite del bosque
Probabilidad
Possible
Tamaño
1–2
You may be able to trigger wind slab avalanches that involve only some of the snow that fell in recent days. The size and chance of triggering these slides increase significantly as you climb into windier, alpine terrain at upper elevations. These avalanches could step down to the buried weak layers described in Problem #1 above as snow moves downslope.

Wind slabs often form near ridgelines and in cross-loaded areas on the sides of gullies. In the Boulders and Pioneers, wind-driven snow also forms slabs in cirques and aprons below large cliff faces and couloirs. You can reduce the odds of triggering a wind slab by looking for and avoiding slopes with obvious signs of wind-loading, such as new cornice growth and large dunes or pillows of wind-blown snow.

Additional Discussion: Any extended periods of sunshine today may produce loose snow avalanches (sluffs) in very steep terrain sheltered from the wind. These slides can be deceptively powerful and can trigger larger avalanches as they move downslope. Pay attention to the terrain above you, and minimize the time you spend below large cliffs and couloirs.

Avalanche Discussion

Don’t let sunny skies fool you into a false sense of stability today. The recent storm deposited 1–3 feet of snow (1.5–2.5 inches of snow water equivalent) in this zone, and the snowpack will need time to adjust to the added weight. In the past few days, numerous natural and human-triggered avalanches have been reported across the forecast area:

Yesterday:
- Snowbikers remotely triggered a large avalanche from below in alpine terrain in the White Cloud Mountains.
- Ski guides triggered a large avalanche while performing avalanche mitigation work with explosives in terrain closed to the public in the Soldier Mtns.
- Scott and others observed over 100 natural avalanches that released in the past few days in the mountains near Galena and the Western Smokys.
- A forecaster saw a very large natural avalanche in the southern Sawtooths.
On Sunday:
- Multiple parties reported remotely triggered avalanches near Galena Pass.
- In the foothills south of Stanley, a forecaster remotely triggered a small slide from a ridgeline and experienced widespread snowpack collapsing.

These are just a few key observations. For more, visit the Observations Page.

Although the loading has stopped, recent reports of both natural and human-triggered avalanches make us wary of entering avalanche terrain. Persistent Slabs won't always present with obvious signs of instability, assume weak layers exist on most slopes.

It's often said that weak layers are guilty until proven innocent, and recent observations show that mid-December weak layers are still proving to be a concern. Hedge your bets by skiing or riding slopes one at a time, and seeking non-wind loaded slopes. Choosing to ride in non-avalanche terrain is an appropriate way to manage today's avalanche problems.

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