Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

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

In sintesi

You could trigger a large avalanche where the wind has formed drifts and stiffened the snow surface. Anticipate loose snow avalanches in very steep, rocky terrain receiving direct sun. Cornices are large and may be unstable—give them a wide berth. 

Problemi valanghivi

  • Wind Slabs

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

    Recent snowfall and strong SW and W wind built 1-2' thick slabs in areas exposed to the wind. As you climb into windier upper elevations, these slabs will be thicker and found in more terrain. On some slopes, slabs formed on crusts and/or weak snow, and avalanches could be easy to trigger or break wider than you expect.

    Slabs often form near ridgelines, along steep mid-slope gullies, or on aprons below steep cliffs. You can reduce your chances of triggering a wind slab by avoiding slopes with obvious signs of wind-loading, such as new cornice growth and large dunes or pillows of wind-blown snow. Some slabs may not be obvious from a distance. A sudden stiffening of the snow you're traveling through, or cracks shooting from your skis or sled can indicate an unstable slab.

    Additional Discussion - Cornices: Cornices are large and may be unstable. Yesterday, we easily triggered a 200' wide and up to 8' thick section of freshly formed cornice. Warming temperatures may cause overhanging cornices to sag and fail. Limit time beneath these features and give them a wide berth when traveling along ridges. 

    (2/24/2025) Large natural avalanche near Copper Mountain. Photo: Ben VandenBos

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Expect loose snow avalanches on very steep, rocky slopes receiving direct sun. Avalanche activity will follow the sun, beginning on SE-facing slopes, shifting to S-facing slopes midday, and more W-facing terrain this afternoon. These slides often initiate near the base of trees and rocks, gathering snow and growing in size as they move downhill. Rollerballs, or pinwheels, signify that the snow is heating up, and wet avalanches may soon follow. 

    While most will start small, they will be plenty large enough to knock you off your feet and carry you into unwanted terrain. Even small slides are consequential above terrain traps such as gullies, creeks, and thick timber. Plan your day to avoid lingering under steep, sunny slopes.

    (2/20/2025)Several Loose Wet slides on the steep, craggy terrain near the Boundary parking lot. Photo: Sawtooth Avalanche Center

Avalanche Discussion

Topping the problem list are wind slabs. Numerous slab avalanches were observed during the storm, and strong wind Monday night into Tuesday built large, sensitive cornices and drifts that remain a concern today.

Today is the first in a string of warm, sunny days. Today's sunshine will quickly melt soft, dry snow at the surface, causing loose snow avalanches. Warm afternoon temperatures will aid in meltwater production at the surface, which may become wet and mushy. This wet snow may slide far and fast on crusts beneath the surface. The timing of wet snow avalanche problems varies greatly with location, aspect, and elevation and is nearly impossible to predict. Build this uncertainty into your travel plans and limit time on or under steep, sun-drenched slopes. 

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