Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Precipitation is expected to return to the West South on Thursday. Although unlikely, deep layers in the snowpack could still fail until a new surface crust sufficiently bridges them. Be suspicious of large open slopes where you're more likely to encounter one of these widely breaking avalanches. 

Problèmes avalancheux

  • Deep Persistent Slabs

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

    As the snow surface slowly freezes and stabilizes, we'll begin to bridge deep persistent weak layers, making them unlikely to trigger. That doesn't mean it's impossible, however. A cornice collapse or other large trigger could do the trick.

    Facets on or just above the Early February Crust produced numerous avalanches over the past month.  Recent observations from the crest indicate that these layers could still be reactive. As recently as Monday, wide-breaking avalanches were spotted from Crystal and are suspected to have failed on these layers. Just across the Cascade Crest in the East South, wet slabs failed on these same interfaces last weekend. Any avalanche occurring on these weak layers would be 3-6+ ft deep, very wide, and likely unsurvivable. 

    (3/18/2024)

    A widely breaking avalanche in Mount Rainier National Park. It likely occurred on 3/18 and may have broken on persistent weak layers.

    Smaller wet avalanches can be see in the foreground. 

    Photo: Crystal Mountain Pro Patrol

Avalanche Discussion

Temperatures are expected to continue to fall as wind and precipitation increase. The bulk of the activity will be on Wednesday night, with a few inches of snow possible at mid to upper elevations and rain likely lower down. With periods of moderate winds, you could encounter a few shallow slabs on leeward slopes on Thursday morning. They shouldn't be very big but don't get tripped up by one near a terrain trap or in a confined gully.

Below the rain/snow line, the snow surface may be wet and punchy. It should be well suited to handle the predicted water amounts. Be mindful of lingering shed-style avalanches such as cornice failures, glides, or the rogue wet slab anywhere additional liquid water has entered the snowpack.

Over the past week, hot and sunny weather has wreaked havoc on our winter snowpack. A quick transition to spring has occurred, resulting in a significant loss of snow and a widespread wet avalanche cycle. The whole spectrum of wet problems has been observed during this timeframe - loose, slab, cornice, and glides. Tree debris, open holes and creeks, and exposed ground have reappeared. They could be hidden by a dusting of snow on Thursday.

Wherever accumulations are light or non-existent, you may need to contend with firm surfaces and potentially long falls. Consider bringing the tools necessary to navigate this travel hazard.

Régions couvertes