Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

Where the snow remains dry, it is likely to trigger an avalanche in wind-affected snow closer to the Cascade Crest. Look for signs of instability, such as cracking, collapsing, and recent avalanches. As an atmospheric river moves into the zone, the likelihood of encountering a dangerous wet snow avalanche will increase. If you're still out in the late afternoon hours and getting heavily rained on, avoid avalanche terrain. 

Problemi valanghivi

  • Wind Slabs

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

    The East Central zone will see dense snow on Saturday, accompanied by moderate wind from the west and southwest. The most snowfall will occur further west and closer to the Cascade Crest and fresh slabs will be deeper in these areas. Older and even deeper slabs could still have some lingering sensitivity. Warm temperatures and the possibility of rain will weaken cornices, causing them to break off and fall more easily. A triggered wind slab could "step down" and become a more treacherous persistent slab avalanche where poor snowpack structure exists.

    Wind slabs usually form just below ridgelines and on exposed convexities and gullies. Visual clues such as cornices, rippled snow surfaces, and dunes will help you identify where the wind has transported snow. Give cornices a wide berth when standing above and below them. Avoid exposed terrain steeper than 35 degrees if you get cracks shooting from your equipment, hear or feel a collapse, or see recent slab avalanches.

    (2/21/2025)

    The crown of a small skier triggered slab avalanche on Blewett Pass (02/21).

    Photo: Payton Schiff

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2

    This problem encompasses our ongoing persistent slab problem and any wet snow problems you might encounter tomorrow. An incoming atmospheric river (AR) will impact the zone more significantly in the later afternoon hours on Saturday. You probably won't see a wet slab avalanche for most of the day, but once the AR hits, it hits hard and the likelihood will rise rapidly

    There are two weak layers in the snowpack: the January Drought Layer (JDL) buried 2 to 3 feet deep and the 02/13 buried around 1 foot deep. If these layers are wetted by rain or melt, they will rapidly destabilize. Where the snow remains dry, an avalanche on these layers is unlikely, but not impossible. The most suspect areas to trigger a slide are on wind-loaded slopes.

    Small loose wet avalanches are more likely with warmth and some rain below 6000 feet leading up to the main AR event.  Additionally, you might see cornices sag and collapse. Wet snow avalanches can travel further and fan out wider than expected. They can initiate from blobs of snow falling from rocks or cliffs. The heavy debris can be difficult to escape from. If you begin to see signs of the snowpack wetting and weakening, mark that as a time to step back from avalanche terrain.

    (12/29/2024)

    The debris of a large natural wet avalanche from earlier in the season in the East Central zone.

    Photo: Rob Pollard

Avalanche Discussion

The incoming AR event will rapidly increase avalanche hazard in the last few hours of Saturday as freezing levels rise even higher and heavy rain starts. Plan your day so that you are not still in or below avalanche terrain by later in the afternoon. Take a look at other zones in the forecast region with higher hazard or Avalanche Warnings to get an idea of how quickly things will change once the bulk of the AR arrives.

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