Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

To reduce the chance of triggering avalanches, avoid slopes where the wind recently formed drifts or slabs. In areas more protected from the wind, triggering a 1-2 foot thick avalanche is less likely but not out of the question. Pay attention to the consequences of being caught in even small slides in terrain with rocks, cliffs, trees, and terrain traps.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    What is it?  Although it's not likely, the most plausible way to get in trouble is in wind-affected alpine terrain, which Ethan explains in the video to the right/above. Ski guides in the Pioneer Mtns recently backed off getting into this similar terrain. Surface hoar is buried down 1-1.5 feet, but is getting harder to find in this zone. 

    Where is it? Older weak layers (crusts and/or facets, occasionally surface hoar) can be found in rocky, wind-affected, alpine terrain where the snowpack is less than about 3 feet thick. The surface hoar is most problematic in somewhat protected, middle-elevation terrain that faces NW-N-NE. It has only been found near Titus Ridge (report here) and on the northern side of Galena Pass. These layers are most likely triggered on slopes steeper than about 35 degrees. 

    How can you recognize it? Wind-loaded slopes have harder surfaces and a distinct appearance of pillows or lens-shaped slabs of snow. You may or may not experience snowpack collapsing and/or cracking while traveling. These red flags are obvious signs of instability. 

    How can you manage it? You can reduce your risk by avoiding very steep (greater than about 35 degrees), shady slopes (facing NW-N-NE) with hard or stiff wind-blown snow at the surface—especially those with ugly consequences if you are caught in an avalanche. Persistent slab avalanches may break wider than expected or higher on the slope above you. 

    ADDITIONAL DISCUSSION: Recent moderate to strong NW winds have created dense slabs in exposed middle and upper elevations, capable of producing small avalanches. You may find wind slabs near ridgelines, on the sides of gullies and chutes. Cracks shooting out from your skis or sled are an obvious sign of instability. Watch for drifts, dunes, and ripples on the snow surface. Wind slabs can have a smooth, chalky appearance and feel and sound hollow, like a drum. The easy move is to avoid obviously wind-loaded slopes steeper than about 35 degrees.

Avalanche Discussion

Alpine terrain sits at the top of my list for triggering larger avalanches. Winds have scoured and transformed the snowpack to have variable depths in the upper elevations. It is in these locations where it remains possible to get closer to thin spots in the slab. Those trigger points could cause a weak layer to fail and propagate across a big bowl, creating a much larger avalanche. You can manage this problem by avoiding slopes steeper than about 35 degrees where rocks and bushes are exposed, and wind-affected snow is present in alpine terrain.

Surface hoar that was buried in early January is not as widespread here as it is in the Sawtooth Mtns and Banner Summit zones. The most recent avalanche occurred near Titus Ridge on January 29th (report). The distribution of this layer seems isolated to mostly sheltered, middle elevations on slopes that face NW-N-NE on the north side of Galena Summit. While it is getting harder to find the right slope with larger surface hoar and steeper than about 35 degrees, it can't be completely ruled out yet. 

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