Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Particularly dangerous wet avalanche conditions continue thanks to a prolonged period of warm sunny weather. These slides are challenging to predict and navigate. Look for ways to limit or even eliminate any time on or underneath steep open slopes.

Problèmes avalancheux

  • Loose Wet

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

    A prolonged wet loose avalanche cycle continues. In some parts of the zone, it’s been more widespread than others. The majority of these slides only involved the surface snow and were relatively small. More will almost certainly occur on Monday. A frozen surface will limit this issue to start the day, but as it melts, you may trigger these slides, or they could occur naturally. 

    In large rocky terrain, some of these avalanches could gouge into older snow, grow larger, and travel far downhill. This much scarier version of wet loose slides is very difficult to predict. Stay out of these areas and minimize the time you spend in their runouts. 

    Other “wet avalanches” like cornice falls, glides, and snow shedding from rocks could occur. These overhead hazards fit right in with this spring-shed theme. Unlike the wet loose, these slides don’t care about time of day and can occur at any hour. Pay attention to what’s above you and if you travel in avalanche terrain, certainly don't loiter.

    (3/15/2024) Photo: Amanda

  • Deep Persistent Slabs

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

    Plenty of uncertainty continues to surround the deeper persistent weak layers in the snowpack. This warmup isn’t helping. Facets on or just above the Early February Crust produced numerous avalanches over the past month. Wet slab avalanches failed on these layers near Ahtanum Meadows (East South), close the the Cascade Crest. While you aren’t like to trigger these slides, a cornice fall or small wet loose certainly may. These avalanches would be 3-6+ ft deep, very wide, and likely unsurvivable. 

    This is just one more reason to stay out of large avalanche terrain during this prolonged period of spring weather.

    (3/15/2024)

    Two widely breaking avalanches near ridgelines. They have an unknown failure date.

    Photo: Andy Harrington

Avalanche Discussion

This is the first major warm-up of the spring, and it’s a doozy. Sunday night will be the fourth above freezing. Often we look at three as a benchmark for an increase in avalanche activity. In some ways, Monday will be a lot like Sunday, but with each additional hot day, our uncertainty grows. 

Wet avalanche cycles like this are the hardest forecast we make. There is no simple observation to let you know the scales are tipping, and often, the danger remains elevated for days. All of these factors make managing these conditions very difficult for backcountry travelers. Avoidance becomes the primary tool. 

Observations from Sunday continue to highlight ongoing wet loose activity. A few small cornice falls were noted on Mt St Helens and Mt Rainier. Larger crowns higher on Rainier have been observed this week, but their timing is uncertain. Ultimately, this multi-day cycle isn’t finished yet, and only time will tell when peak danger actually occurred.

Régions couvertes