Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Wed
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Stormy weather is expected to continue, especially on the volcanoes. This should maintain dangerous avalanche conditions in areas favored by the storm track. Note how much dry snow exists and dial back your terrain selection if you see cracking or other avalanches.

Problèmes avalancheux

  • Storm Slabs

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

    Expect snowfall to continue and add another storm layer for you to investigate on Tuesday morning. This flow pattern should again favor the volcanoes, but that doesn’t mean the snow hasn’t started to stack up near the crest as well. You should check for potential points of failure or a poor bond by using hand pits or small test slopes. The warm temperatures mean the storm snow may be “upside-down,” with heavy snow over weaker snow. In wind-exposed areas, slabs could be thicker and more reactive. Triggering an avalanche will be more likely on slopes over 35 degrees, especially if they are convex, unsupported, or wind-loaded.

    (1/22/2024)

    An explosives-triggered slab in steep, rocky terrain. 

    Photo: Crystal Mountain Pro Patrol

  • Loose Wet

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

    We’ve had several days of rain and warm temperatures at lower elevations. The height of wet avalanche activity has likely passed. On Tuesday, we should continue to get rain down low, creating the potential for some lingering slides. We might get some sun breaks in the afternoon, which could help reinvigorate this problem. Regardless of the mechanism for getting the surface wet, consider the potential for these slides anywhere you’re sinking into wet snow past your ankle. They could grow large or trigger slabs as they descend.

    (1/22/2024)

    Rollerballs and other wet loose avalanche activity. 

    Photo: Dallas Glass

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    The poor snowpack structure around the Solstice Crust persists. This problem won’t give you any direct feedback as you travel. Slopes could contain multiple tracks; you won’t see shooting cracks or feel collapses. These slides are erratic and unpredictable. Your best management tool will be to avoid the type of terrain where they are more likely. Big open slopes that are capable of propagating widely and producing a very large avalanche are the areas we’re talking about. 

    (1/20/2024)

    Crowns along the ridge from Scout Pass to Norse Peak. A newly discovered widely propagating avalanche with a 3+ foot crown.

Avalanche Discussion

It was another relatively warm and stormy day on Monday. NWAC forecasters near Crystal Mountain reported triggering several small wind slabs during their travels and a few small wet avalanches at lower elevations. They also found another very large avalanche that failed sometime in the last week. 

Across the street at Crystal Mountain, the Pro Patrol reported large and sensitive cornices with sensitive wind slabs propagating on the slopes below. At White Pass, Pro Patrol reported heavy, wet snow that they could push around in steeper terrain.

Expect similar conditions on Tuesday, with avalanche size and likelihood higher on the volcanoes than near the crest. But take a look at how the weather is unfolding in your area. Anywhere you find more than six inches of dry snow, you should think about new snow avalanches. If the snow is wet, think about pushing wet avalanches on steep slopes.

Our friends at the USGS sent us information about two potentially very large avalanches on Mount Rainer. Their seismic equipment picked up signatures that roughly equate to D4 avalanches. They occurred on the mornings of 1/21 and 1/22. NWAC hasn’t confirmed them, but the USGS has a good track record when it comes to reporting these kinds of slides.

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