Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

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

In sintesi

Very dangerous avalanche conditions will develop throughout the day and peak overnight. Expect 1-3 foot thick avalanches to release on their own. Avalanches are most likely in areas exposed to the wind. You may be able to trigger avalanches 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
    Very Likely
    Dimensione
    1.5–2

    Large Persistent Slab avalanches are expected to release naturally. Today's storm will form slabs on a mix of weak snow surfaces, including facets, surface hoar, and crust + facet combinations on slopes that face the sun. The widespread nature of this weak layer means avalanches may be easy to trigger on many aspects and elevations by day's end. 

    Conditions are most dangerous where wind-blown snow forms thick, stiff slabs at the snow's surface. As storm snow piles up, your odds of triggering an avalanche will also increase on steep slopes at middle and low elevations that are more sheltered from the wind.  

    Persistent Slabs can release in surprising ways, break wider than expected, and release hundreds of feet away from where they are triggered. Avoid wind-loaded avalanche terrain; this includes flat terrain below steep slopes.

    Additional Discussion: While less likely, avalanches may fail in weak snow near the ground. The resulting avalanche would be very large enough to destroy a house. This scenario is most likely on shaded NW-N-NE facing slopes above about 8,000'. 

    (12/1/2024) This is an example of the wide, large avalanches we expect to see during the storm. This slide occurred in the N. Boulders after our last significant storm. 

    Photo: Sawtooth Avalanche Center

Avalanche Discussion

Avalanche danger will rise steadily throughout the day, peaking late this afternoon and overnight. The Banner Summit Zone is expected to pick up anywhere from 7-13" of snow by day's end, favoring the mountains near Cape Horn, Copper Mtn, and Banner Summit. Today's danger directly relates to how quickly a slab forms at the surface. Windier middle and upper elevations will get a head start, building stiff slabs that will release naturally and be very easy to trigger. The danger is slower to rise in areas more sheltered from the wind. Here, subtle wind press and consolidating snowfall will gradually form touchy slabs throughout the day.

In either case, we're building on a shaky foundation, and don't expect today's storm snow to play nicely with the myriad of weak layers we're loading (see examples below.) 

Regioni coperte