Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Warming temperatures and sun will maintain concern for falling cornices. You may be able to trigger loose avalanches on very steep northerly slopes as well as on sun-exposed slopes. Move off of sunny slopes and cornices before they become weak and unstable.

Problemi valanghivi

  • Loose Wet

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

    A warming trend with sun will continue into the weekend. Watch for triggering small, loose wet avalanches on steep solar slopes. Time your travel to be off of these slopes before the surface snow becomes weak and unstable. Use caution around terrain traps such as gullies and cliffs where small avalanches could be dangerous. You can also trigger dry loose avalanches on slopes steeper than 40 degrees. 

    (3/11/2021) An example of loose wet avalanches from the Stevens Pass zone. These ran on either March 9th or 10th. Rock Mtn, SE, 6,400ft.

  • Cornices

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

    Avoid lingering on or under large cornices. A falling cornice could be big enough to injure or kill you. Give them a wide margin as they can break further back onto the ridge than you may expect. Exposed rocks and vegetation on a ridge can be indicators of where to stand above part of the mountain and not on unsupported snow. 

    Saturday's warm temperatures and sun could be enough to bring down more cornices from where they're overhung and unsupported. I watched one fall in Copper Creek on Monday. Last week, cornice fall resulted in avalanches that wouldn't have otherwise run naturally. 

    (3/8/2021) Large cornices sagging high above the Hairpin Valley.

Avalanche Discussion

On Monday, I checked out a variety of slopes at Washington Pass in the Hairpin Valley and beyond. We triggered small loose dry avalanches, a very small wind slab, and watched a natural cornice fall. You may find some of these conditions on Saturday. Shallow wind slabs that built early in the week are now difficult to trigger. The snowpack is generally strong, deep, and without any layers of concern. In the top 2 feet of the snowpack, I did find a couple of interfaces with strong-over-weak layering. Investigating these interfaces revealed no signs of instability or reasons for concern at the time.  A widespread avalanche cycle occurred in the zone around February 22nd and many crowns and debris piles are still visible. Further east, the snowpack is more shallow and could potentially harbor persistent weak layers, though an avalanches on these layers is unlikely at this time.

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