Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger will rise through the day as a storm moves in and temperatures warm up. Shift to simpler, lower-angle terrain during stormy periods or if you see signs of instability like shooting cracks, rollerballs, or fresh avalanches.

Problemi valanghivi

  • Storm Slabs

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

    The incoming storm isn’t arriving cleanly—expect variable snowfall rates, fluctuating snow levels, and shifting winds. Avalanche danger could rise quickly in the afternoon or evening, especially during heavier snowfall, but shallow, reactive slabs may exist from the start. Conditions will vary widely across the zone, with more precipitation near the Baker Backcountry and less along the Canadian border and in North Cascades National Park.

    You are more likely to trigger a slab on steep slopes that are loading up with wind-drifted snow. But with weak, faceted snow or crusts at the current snow surface, be ready to see shallow slabs in all terrain, wind-loaded or not. Track conditions through the day. As snowfall, wind, and poor visibility increase, step back from bigger, steeper, and more complex terrain.

    (12/16/2024)

    You could find the slab in wind-sheltered terrain on Wednesday. Weak snow surfaces mean you might see some reactivity even with modest amounts of new snow.

    Photo: Gregg Oliveri

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Wet loose avalanches should be on your radar at low and middle elevations as rising snow levels spit rain onto a bit of new snow. While all should be small, they can still pose a real hazard in rugged, marginally snow-covered terrain or where open creeks exist in the runout. Avoid travel on or directly beneath steep slopes where you see fresh rollerballs, pinwheels, or small wet avalanches.

    (1/20/2024)

    Rain on new snow is a near-guarantee of snow sliding down the hill.

    Photo: Julz Holder - Grounding Truth

Avalanche Discussion

West North has been the outlier forecast zone over the last few days, with more snow and avalanche activity over the weekend and into Monday than anyplace else in the Cascades. Precipitation amounts haven't been especially noteworthy, nor have avalanches been very large, but the 4-10 inches of new snow just haven't bonded well to the crust layer just below it. This weak interface produced numerous loose snow avalanches and some slabs as well. The snowpack beneath recent snow is a mix of crusts with rounded grains and soft melt forms—a product of repeated swings between cold, snowy weather and warmer, rainy periods this winter.

The most important factor heading into the next storm is the current snow surface. Light-density surface snow has faceted, with weak snow lingering even on sunnier aspects where you’d typically expect to only find melt-freeze crusts. A few days of faceting alone isn’t a classic setup for a persistent weak layer, but it is enough to increase sensitivity. Expect fresh slabs to be more reactive than usual, even with relatively moderate amounts of new snow.

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