Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
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Pericolo valanghe

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

In sintesi

Triggering an avalanche large enough to bury you is likely today in many locations. Travel above 9,000' will be very dangerous with large, natural avalanches likely to occur. You're most likely to encounter unstable slabs one to three feet thick in wind affected terrain near ridge-tops above 7,500' and in steep alpine terrain where even more new snow has fallen and drifted. Avoid slopes with stiff, wind drifted snow or snow that cracks or collapses when you approach.  Avalanches could be larger than expected if they involve the older, weak snow now buried one to two feet or more beneath the surface.

A Winter Storm Warning continues today with 6-12" more new snow accompanied by very strong SW/W winds. 

Problemi valanghivi

  • Wind Slabs

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

    Wind and storm slabs became touchy yesterday afternoon when only 6-8" of the 12-18" of new snow had impacted the Tetons and Greys zones. More new snow falling overnight and today will make the slabs even thicker. The new snow was becoming touchy even in areas not affected by wind.  Remember that the new storm and wind slabs sit on weak snow that faceted into loose, unconsolidated grains due to the cold, drought conditions that occured in December.

    The 8-12" of new snow that fell yesterday was light and dry. Snow continues today and in wind sheltered locations without a slab, you'll find sluffing of the new snow and older facets to cause a different kind of problem. Keeping terrain choices mellow today is a wise choice, particularly considering the weakness of older buried layers as discussed in avalanche problem number two. 

     

    (1/9/2024)

    Twin Slides on Mt. Glory slid twice yesterday. Areas like this reloaded again overnight and could easily be triggered again today but would be larger.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    We now have two weak layers of snow to track from dry spells in November and December. This more recently formed layer of near surface facets and surface hoar are now buried around 2 feet deep . Unlike the deeper weak facets, this layer is much more likely to be reactive today anywhere a slab has formed over it. The layer is one to two feet down and showed a tendency to fail yesterday in stability tests and in avalanche activity. The weakness of this layer could make the new storm and wind slabs crack and fail greater distances,  or entrain more snow.  

    Weak snow that formed during November now sits about three feet below the surface but has been  dormant in the past month.  Avalanches on that layer seem unlikely but cannot be ruled out in steep, north-facing terrain at the upper elevations.  This layer may wake up and fail as we add additional load to the snowpack. Moving avalanche debris could conceivably step down to this layer.

    (1/7/2024)

    Well preserved, large surface hoar in the top 30 cm (12") of the snowpack prior to the new snow. This layer received another foot of snow on top yesterday and will get another foot today. This may prove to be the proverbial house of cards where that surface exists.

Avalanche Discussion

Six hundred miles of wind on the summit of JHMR, touchy new snow and weak layers should have your hackles up today. An out and back ride on a ridge yesterday in the northern Snake River Range made it clear that the new snow and wind combined to easily build drifts that not only filled our tracks but built three foot drifts in our path in a few locations. There's plenty of bullseye information today that highlights the need for caution today. 

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