Bollettino valanghe

Snake River Range

Bridger-Teton Avalanche Center
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Pericolo valanghe

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

In sintesi

Avalanche conditions are becoming dangerous. New snow and wind have built sensitive slabs less than 1 foot thick on weak snow surfaces at middle and upper elevations. These slabs will grow larger - and more sensitive - as snowfall and strong winds continue. Choose terrain < 30º to reduce your risk. 

The NWS has issued a Winter Storm Warning that is in effect until Sunday, 11:00 PM

Problemi valanghivi

  • Wind Slabs

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

    Southwest winds with 4 inches of new snow have built wind slabs less than 1 foot thick on leeward slopes at middle and upper elevations. These slabs formed on top of a variety of surfaces including facets and crusts and may be sensitive to the weight of a human. Expect the sensitivity and size of these slabs to increase as heavy snowfall and strong winds continue today. Slabs may grow into the 1-foot range by mid-day at upper elevations. Use caution in terrain where wind slabs typically form - ridgelines, cross-loaded gullies, and leeward slopes. Watch for obvious signs of unstable snow such as cracking, collapsing, or recent avalanches. The formation of drifts, fresh cornices, or blowing snow will give you an early indication of where slabs may be forming. Pay attention to rapidly changing conditions as the storm continues today. Seeking lower-angle or wind-sheltered terrain will help reduce your risk.

    Storm snow instabilities may be found in terrain sheltered from the wind at all elevations. Assume that the new snow will be unstable while traveling in the mountains. Use safe travel practices today, and keep an eye out for terrain traps where even a small avalanche can have large consequences.

    An example of a slab failing on a weak old snow surface

    Photo: Bridger-Teton Avalanche Center

  • Persistent Slabs

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

    You are unlikely to trigger an avalanche failing on faceted snow near the ground. There has been no observed activity on buried weak layers in the Snake River Range for the past 3 weeks. Even so - very steep, wind-scoured, rocky terrain remains the most suspect.

    (1/30/2025)

    This persistent slab avalanche demonstrates the isolated nature of this problem.

    10,400' NW Gros Ventre Range. 

    Photo: Bridger-Teton Avalanche Center

Avalanche Discussion

A prolonged period of dry weather has come to an end. This dry period created a variety of snow surfaces with a range of distributions. Crusts on west-south-east aspects, weak faceted snow on west-north-east, stiff windboard on east-north-west in the upper elevations, and facets on many aspects in the lower elevations. Regardless of the previous snow surface, you can expect to find instability within the new snow today. Continued snowfall throughout the day will continue loading slopes, and you'll likely find rapidly changing conditions. Slopes that may have shown no signs of instability in the morning could produce avalanches by the afternoon. Areas that are subject to strong winds will be more prone to avalanching. Today is a good day to stick to lower-angled terrain and use avoidance as the primary tactic for managing new snow instability.

If you see avalanche activity today, I ask that you please consider submitting an observation HERE. Observations allow everyone to gain a better and more complete understanding of conditions. Thanks!

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