Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

New snow and sustained ridgetop winds will continue into Tuesday. You can trigger large, destructive avalanches in wind drifted terrain, especially in the alpine. Natural avalanches at upper elevations may impact lower elevations. Avoid consequential avalanche terrain. 

Problemi valanghivi

  • Wind Slabs

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

    Several feet of new snow and moderate to strong winds have created a patchwork of instability on the new / old snow interface. For reference, the Heather Meadows weather station recorded ~3inches of SWE and ~36 inches of snow in the 36 hours prior to writing this forecast. We expect another ~1 inch of SWE and/or ~12” of new snow by Tuesday afternoon. 

    Visibility is limited, but many natural and human triggered avalanches occurred Sunday night and Monday. Although the peak avalanche cycle probably occurred early Monday morning, continued new snow and S-W wind will keep things touchy well into Tuesday afternoon.

    This is a good day to limit your exposure to avalanche terrain. Stick to shallow slopes (under ~30 degrees in steepness) that aren't connected to upper elevation start zones, or other significant overhead hazard. Overhead hazard refers to an avalanche slope that threatens the area below it. 

    Shooting cracks and whumpfing collapses are red flag signs of instability and should drive you to lower angled terrain.

    Photo: Robin Pendery

  • Deep Persistent Slabs

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

    Two explosive triggered avalanches and two natural avalanches were triggered deep in the snowpack on the Shuksan Arm since Christmas. Check out one of these avalanches HERE. All of them occurred on steep, unsupported alpine terrain features. 

    There is uncertainty around the layer in question, but it seems to be a layer of surface hoar which was buried prior to Christmas. Visibility is poor and information is sparse, so we don't know how widespread the layer is, or how many avalanches it may have produced during the current loading cycle. 

    The continued possibility of very large avalanches triggered deep in the snowpack is another reason to steer clear of large, wind-loaded slopes and the terrain beneath them, even if the area is flat.

    (1/1/2022)

    Surface hoar crystals found on the bed surface of the very large deep persistent slab avalanche which failed naturally on the Shuksan Arm on 12/31.

    Photo: Irene Henninger

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