Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 9 months ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Another round of heavy rain, and warm temperatures, will impact the cascades Monday night, tapering off Tuesday morning. Wet avalanches are possible at low and mid-elevations, switching to dry slab avalanches above the rain-snow line. Pay attention to the surface snow as you travel, and assess steep slopes before committing. 

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    This problem is confined to upper elevations, where rain transitions to snow. If you're headed into this terrain, the key will be to identify the change in avalanche hazard. Storm slabs may develop anywhere more than a few inches have built up. Total snow accumulations will increase with elevation, also increasing the risk of larger slabs. If triggered, these slabs could fail as deep as the new snow. Expect to find deeper, more sensitive slabs where wind drifted snow has also collected. Use small test slopes, and visual observations, such as natural avalanche activity, to search for instability.  If in doubt, stick to terrain below 35 degrees.

    (12/26/2024)

    Storm slab example: large slab avalanche that occurred naturally in steep rocky terrain at Crystal Mountain on 12/26/2024.

    Photo: Crystal Mountain Pro Patrol

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Wet avalanche activity continues to be a concern at low and mid-elevations, where large amounts of precipitation has saturated the snowpack.  In areas of greater snow coverage, such as mid-elevations, these avalanches could be large enough to bury a person. These avalanches often start at a single point, and fan out below, entraining more snow as it slides. If the snow under your feet feels slushy, and unsupportable, so are the steep slopes. As temperatures decrease through the day, sensitivity of these avalanches may as well.

    (12/6/2025)

    A natural point release (loose wet) avalanche from a recent rain on snow event.  (Silver Basin, 6600ft, east aspect, WL-N-D1-R1)

    Photo: Dallas Glass

Avalanche Discussion

Extended rainfall continues to decimate low and mid-elevation snow depth, leaving most trailheads completely devoid of snow. A cooling trend is expected Tuesday morning, significantly lowering snow levels. The uncertainty lies with how quickly this cooling trend will occur, and how much precipitation will be leftover to snow. For those headed to upper elevation terrain, expect winter-like conditions with more elevation. That also means changing snow conditions, and different avalanche problems. For those staying in low and mid-elevations, expect soggy conditions, firming up later in the day.

With the warm start to the 25-26 winter season, we have less snowpack information than usual to start daily forecast operations. For zones and elevation bands with less snow than needed for avalanche hazard, we will issue a forecast with No Rating. Anticipated avalanche and weather conditions will still be updated daily. NWAC will issue an avalanche danger rating for a zone when enough snow to produce avalanches has accumulated at middle and upper elevations.

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