Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
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

Triggering an avalanche at and above treeline will be possible for Monday on all  slopes where wind has loaded recent storm snow. With variable wind directions, this may be seen in atypical slope locations on all aspects at these upper elevations. Use visual surface clues (blowing snow, below ridges and cornices, smooth pillowed surfaces) to understand where this avalanche problem exists, and avoid any steep slopes that show these signs of instability. Large human triggered avalanches also remain possible in isolated terrain near treeline and below treeline on west, north, and east facing slopes where a weak layer of old snow may be present. If there is any uncertainty of the snowpack's stability, stick to lower angle slopes that are less than 30 degrees.

Problemi valanghivi

  • Wind Slabs

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

    As the clearing pattern continues for the first time since a procession of storms brought over 2' of snow to the Central Cascades, many backcountry users eyes and ambitions may turn upwards to higher elevations. Sustained cold temperatures since the snow started falling again (after the January drought) has resulted in an abundance of low density snow to be available for wind transport. With variable wind directions over the next 24 hours (W -> E -> N), we could see pockets of reactive wind slab in unusual locations, on all aspects at and above treeline, or any open slopes where wind could have loaded recent snow. Careful assessment will be necessary before stepping out into higher consequence terrain where wind loaded snow may be present.

    Mt Bachelor Ski Patrol, using explosives and ski cutting, triggered several pockets of reactive wind slab on Sunday in above treeline terrain that had not seen any human traffic since before the latest rounds of storms. If you chose to venture in to higher elevation terrain, use small, low consequence indicator slopes to check for wind slab reactivity before committing to leeward terrain. If cracking in the slab or recent avalanches are observed, this is a good sign to step back and seek lower angle terrain.

    (2/9/2025)

    D1.5 Wind slab avalanche triggered by Mt Bachelor Ski Patrol on 2/9 using explosives. SE slope @ ~ 8400 ft.

    Photo: Leslie Norberg

  • Persistent Slabs

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

    Recent observations show that our PWL, or Jan 31 buried facet layer, appears to be gaining strength, or 'rounding'. Recent stability tests on this layer show promising results for this trend, however the weak layer (and therefore weak snowpack structure) is still present, despite it becoming more stubborn to trigger an avalanche. This being said, Persistent slab problems such as this one are notorious for having wide spacial variability, and certain terrain features (e.g. convex slopes and shallow rocky areas) could see a greater likelihood for triggering an avalanche on this PWL. With this stabilizing trend we will be less likely to get our typical red flags like collapses and whumphs, even when a reactive slab is present. Patience and continued caution remains necessary, with more planar slopes being the safer terrain choice. If a Persistant slab avalanche were to trigger, it could result in a large, potentially fatal slide.

    (2/8/2025)

    The January 31 buried facet layer is easy to find in the snowpack under the recent snow (down 32 - 35"). On Saturday, I found it to be gaining strength but it is still weak compared to the surrounding above and below it. 

    Photo: Aaron Hartz

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