Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The chances of triggering a slab have become unlikely, but a weak structure may exist at upper elevations. Check for weak snow about a foot down, on or beneath a thin crust as you travel and gain elevation. Consider this before comitting to steeper more complex terrain where even a small slide could have increased consequences. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–1.5

    Slabs have become stubborn, but still, it wouldn't be impossible to trigger one in the wrong place. Southerly and easterly winds over the past week may have formed thick slabs on a variety of slopes. In some places these slabs may rest on a thin crust with weaker snow underneath. In the right (or wrong) place, you could get surprised by slab on this layer. It would likely take a large load like a snow machine, or a large cornice fall.

    Terrain awareness is one way to let this knowledge influence your decisions. Consider steering around features with an overall thin snowpack, though look to hold thicker slabs from recent loading. Steep, rocky, and shaded slopes like unsupported cliff bands come to mind. If you observe any cracking or whumphing collapses, then retreat to lower angled slopes. 

    (12/26/2023)

    A natural wind slab avalanche in steep rocky terrain. Note the cornice line above it. [N-SS-D1-R1-U]

    Photo: Zach Winters

Avalanche Discussion

Temperatures have been on a slow but steady rise. Observers reported some moist snow and pinwheeling on Friday. Expect more of the same on Saturday. Some steep slopes at lower elevation could even produce small loose wet slides in the right place.

Small, natural wind slabs were reported from upper elevations the 26th and 27th. An interesting slide from Pica Peak on the 26th appears to have stepped down to a deeper layer. Although this structure is gaining strength, this slide supports the idea that buried weak layers could still be a problem in some areas. The layers may include buried surface hoar, and/or faceted grains sandwiched between brittle crusts, and could be up to 1.5ft down. You're most likely to find these on W-N-E aspects where the sun hasn't played a role. As you travel, take note of snowpack structure with small hand pits, pole probes, etc. This could be a good time to use compression tests, ECTs and PSTs if you do find a weak structure. We have limited information for areas outside of Washington Pass, but weak structure could be more prevalent in areas with a shallower snowpack such as the Pasayten.

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