Bollettino valanghe

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Sat
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Very dangerous avalanche conditions exist. With another stormy day on tap, avalanches are most likely in windy terrain. Some have the potential to be very large, releasing a 3-6 foot thick, unsurvivable avalanche. Slides can be triggered remotely—from flat terrain below, above, and to the sides of steep slopes.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3.5

    Several days of heavy, dense snowfall, rain, and warm temperatures formed thick, meaty slabs on most middle and upper elevation slopes. These slabs may fail on deeply buried facets or crusts in the upper 3' of the snowpack.

    Faceted snow in the lower part of the snowpack is buried 2-5 feet deep on W-NW-N-NE-E-SE-facing slopes at middle and upper elevations. On Wednesday in the Boulders, a skier triggered a very large avalanche involving this layer. The slide broke ~1/4 mile wide and averaged 3-4' thick. Similar massive avalanches were observed yesterday on Galena Pk (photos). You're most likely to poke this beast 1) where the snowpack is around 3 feet deep and  2) in windy and/or rocky areas where the snowpack depth is variable.  

    Assume a slab + weak layer setup exists on all slopes. You may or may not experience obvious signs of instability—like snowpack collapsing or cracks shooting out from your skis or sled—before triggering an avalanche. You may be able to trigger avalanches remotely—from flat terrain below, above, and to the sides of steep slopes.

    (12/24/2025) This very large avalanche was remotely triggered from low-angle terrain adjacent to a large alpine bowl. Spring Ck in the Boulder Mountains. NW @ 10,200'. Photo: Ben VandenBos

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2

    Expect to find fresh wind drifts and slabs up to 2 feet thick in exposed, upper-elevation terrain. Watch for dunes or smooth pillows below ridgelines and cornices and on the sides of cross-loaded gullies. Cracks shooting out from your skis or sled are an obvious sign that you've found a wind slab. Any wind slab you trigger has the potential to trigger the much larger Persistent Slabs as the wind slab avalanche moves downslope.

    (12/18/2025) Natural wind slab avalanches on a NE-facing slope near 8900' on Copper Mountain. Photo: Sawtooth Avalanche Center

Avalanche Discussion

Additional massive Persistent Slab avalanches were reported in the Boulders yesterday. These slides likely released on Christmas Eve night, failing on weak faceted snow near the ground. We expect avalanches like these to remain likely in this zone where the snowpack is relatively thin. This can be in sheltered terrain that's received less snow in the past 2 weeks, like middle elevation slopes in the White Clouds, near Tornak and Coyote Yurts, Warm Springs Drainage, or terrain either side of highway 75 near and south of Prairie Ck. This also includes windier terrain at upper elevations, where the wind built hard slabs that may be triggered from the margins where the slab is thin. 

 

 

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