Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wednesday will be a transition day as incoming clouds and wind begin to replace our hot and sunny weather. Wet avalanches will be possible until the snowpack has enough time to freeze and stabilize. Avoid large open slopes and be aware of overhead hazards.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Wet avalanche activity should be trending downward. It won't be eliminated on Wednesday, however. Most slides should be loose and confined to the surface snow but could gouge down into older snow in isolated locations. In addition, snow shedding from rocks, cornice falls, and slab avalanches can't be entirely ruled out. Although unlikely, these larger shed-style slides are more dangerous and difficult to predict. Continue to minimize your time in and below avalanche terrain until the surface has frozen later this week.

    (3/19/2024)

    Wet avalanches from 3/19 in the White Pass backcountry.  They cross a common travel route. 

    Photo: White Pass Pro Patrol

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Plenty of uncertainty surrounds the deeper persistent weak layers in the snowpack. Facets on or just above the Early February Crust produced numerous avalanches over the past month.  A recent public observation from the White Pass backcountry indicates that these layers are still reactive in snowpack tests. Widely breaking avalanches were spotted from Crystal Mountain on Monday in Mt. Rainier National Park and could have failed at this interface. Wet slab avalanches were confirmed to have failed on these layers just across the Cascade Crest in the East South last weekend. While you aren’t likely to trigger these slides, a cornice fall or wet loose certainly could. 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

Wednesday will be the start of a transition toward more seasonable weather, with decreasing freezing levels and increasing winds and clouds. It will still be warm but a notch lower than what we have experienced for the better part of the last week. During this hot and sunny period, we've experienced multiple nights above freezing, daytime temperatures soaring into the 50s and 60s, and little wind. These factors have resulted in a multi-day wet avalanche cycle, which peaked at different times in different locations.

The likelihood of this cycle continuing has decreased but not been entirely eliminated. Wet avalanches are notoriously challenging to forecast, and water can linger in the snowpack long after the surface has started to freeze. 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. Continue navigating terrain cautiously by avoiding overhead hazards and staying off steep slopes. As temperatures slowly lower, the surface will begin to freeze, and this cycle will draw toward a close.  Until that happens, wet avalanches remain possible. 

Regioni coperte