Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Large human-triggered avalanches are most likely on slopes where wind has formed drifts and slabs. In terrain sheltered from the wind, triggering large avalanches is less likely but not out of the question. On slopes that face the sun, loose snow avalanches will become likely once surfaces become moist or wet. 

Problemi valanghivi

  • Persistent Slabs

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

    Yesterday, a skier triggered a large avalanche just outside of this forecast zone. Fortunately, they were able to ski off the moving snow. This avalanche likely failed about 2’ deep on the weak sugary facets that formed during the Jan/Feb drought.

    Triggering similar avalanches today is most likely in recently wind-loaded terrain. The recent storm and wind-driven snow buried weak facets, surface hoar, and crust-facet combinations on many middle and upper-elevation slopes. More deeply buried weak layers that formed during the extended Jan-Feb drought (facets, crust + facets, surface hoar) have not healed and remain suspect, primarily on NW-N-NE-E aspects above and below the middle-to-upper elevation transition. 

    Persistent Slabs can release in surprising ways. They can be much wider than expected and be triggered remotely—from flat terrain below, above, and to the sides of steep slopes.

    Avoiding steep wind-loaded slopes is the best way to avoid trouble today. Recognize that avalanches are also possible in more sheltered terrain. Snowpack cracking and collapsing are clear signs of unstable conditions.Additional Discussion: Whether a weak layer exists or not, the combination of recent snowfall and moderate to strong winds formed slabs that may remain sensitive to your weight. Look for wind-affected surfaces, dunes, or drifts.  Feel for stiff slabs overlying weaker or softer snow. These often form near exposed ridgelines. These smaller wind slabs, once moving, are an effective trigger for the larger Persistent Slab avalanches described above.

    (2/21/2026) A skier triggered and skied out of this avalanche. This large avalanche failed about 2' deep, presumably on weak facets that were buried on 2/8. 

    NE facing at 8400'. 

  • Loose Wet

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

    Sun and warmth-induced loose snow avalanches are likely on steep slopes that face the sun. The soft, fluffy surface snow won't take much heat or sun to weaken. Natural and easily triggerable loose avalanches are expected as the day warms. These slides often initiate near the base of trees and rocks, gathering snow and growing in size as they move downhill. 

    Rollerballs, pinwheels, and trenchy trail-breaking are bullseye observations signalling that the snow is heating up, and wet avalanches may soon follow. Even small slides can be consequential above terrain traps such as gullies, creeks, and thick timber. Plan your day to avoid lingering under big avalanche paths longer than needed.

    While relatively small on their own, loose snow avalanches could trigger larger slab avalanches as described above.

Avalanche Discussion

Yesterday, a skier narrowly skied out of a large avalanche near Banner Summit. Two others remotely triggered avalanches near Banner Summit and up Baker Creek (observation). Our current situation is ripe for accidents. A long drought during January and early February left powder seekers eager. During that period, weak layers developed throughout our area. A significant storm finally arrived earlier this week, enhancing the riding conditions but burying those weak layers. In response to the new snow and wind, we experienced an avalanche cycle. Now, a few days have passed, and the likelihood of avalanches has gradually decreased. Obvious signs of instability are becoming less reliable, which may give you a false sense of security while traveling through terrain. The first sign of instability could be an avalanche you trigger. 

The snowpack hates rapid change, and well, today, it's changing. We’re heading into the warmest day since receiving about 2' of new snow earlier this week. As the weather warms, the dry surface snow may turn into denser slabs in shaded terrain. On sunny slopes, the sun and warm temperatures will cause the upper snow to weaken, and we expect to see loose snow avalanches occurring on steep slopes. Either could be enough to trigger larger avalanches, failing on weak layers deeper in the snowpack. 

Many people, myself included, are keen to make deep trenches in the snow. Remember, this will not be the last weekend to ride powder. As we head out to enjoy the snow, we'll be managing our terrain selection by choosing lower-angle slopes without overhead hazards. 

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