Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Saturday night's storm finished warm and wet, creating a weak surface and the potential for avalanches. Hazard should be highest at upper elevations or on the volcanoes. Give the snowpack time to adjust and heal by avoiding steep unsupported slopes, convexities, and overhead hazards. 

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    You may be able to find dry snow below the moist surface and above ~6000 feet. So it is worth considering the possibility of slab avalanches for another day as the snowpack adjusts to the rapid change it just underwent. The snow surface doesn't have to be dry to produce a slab avalanche, but our hunch is that they'll be more likely as you ascend to elevations that got less damp. Be extra leery on steep, unsupported slopes or convex features where you could trigger a slab more easily. They could be stubborn, but if they get moving they will likely grow large and dangerous as they descend.

    (1/5/2025)

    Small natural storm slab avalanches along the valley road just east of Paradise.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    The snow surface is generally wet and weak. Monday is expected to be mostly sunny and freezing levels should be on the rise. Thus, wet avalanches will be possible anywhere you are sinking into wet and sticky snow deeper than your ankle. You could see a variety of issues - wet loose, tree bombs, large chunks of snow falling off rocky ledges, or even cornice collapses. Any of these could then entrain snow and grow large as they descend. They could even trigger lingering slabs. Make travel plans that avoid overhead hazards or terrain traps such as gullies and creeks where even a small wet avalanche could become more consequential. 

    (1/5/2025)

    Wet avalanches were easy to trigger with ski cuts during mitigation efforts at White Pass.

    Photo: White Pass Pro Patrol

Avalanche Discussion

Saturday night's storm finished warm, resulting in widespread avalanche activity overnight and during the day on Sunday. Crystal and White Pass Pro Patrols reported sensitive slabs during their morning mitigation efforts before a changeover to wet problems. Avalanche professionals at Paradise observed natural avalanche activity had occurred at most elevations and that the snow was drier above ~6000 feet. They also reported a poor bond at the new/old interface (1/4) due to repeated propagating test results. In the Crystal area, NWAC forecasters reported a more favorable bond at the 1/4 and a somewhat drier landscape. On Mount St. Helens, a cornice collapse was reported due to the warm and wet weather. 

With a poor overnight refreeze expected and a relatively warm and sunny day forecast on Monday, don't expect the narrative to change much. Weak and wet surfaces at most elevations are capable of producing erratic avalanches. We don't anticipate the same level of avalanche activity, but that doesn't mean everything is good to go, particularly at upper elevations or the southern volcanoes where uncertainty is high. Our hunch is that we're still in store for a few weird slides as this warm week commences. Be prepared to make good assessments and be leery of slopes over 35 degrees if you're trying to take advantage of the nicer weather window.

We have essentially doubled our seasonal snowpack depth over the last two weeks and this storm was a big change to top it off. We had concerns that potentially buried weak layers would fail during the storm. We don't have enough information yet to either confirm or deny activity on these suspected layers, but we can say that below the moist surface, a cold and layered snowpack still exists. NWAC forecasters near Crystal did not get concerning test results on our layers of concern, which is promising. Still, the results at Paradise are not confidence-inspiring. Give the snowpack the time it needs to heal and adjust.

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