Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
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

Small Wind Slab avalanches will be possible on north and east slopes near treeline and at alpine elevations.  Additionally, observers have been finding weak faceted layers and buried surface hoar in the upper snowpack.  These persistent weak layers have not resulted in any avalanches, but are worth investigating before committing to large, steep slopes.

Problemi valanghivi

  • Wind Slabs

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

    Wind Slabs occurr when wind blows snow onto lee (in this case north and east) slopes and packs it into a more cohesive slab.  Wind slabs will be relatively small on Wednesday, but will grow throughout the day as more snow falls.  They may be particularly touchy where they were built on top of surface hoar and near surface facets.  These weak snow crystals formed on Saturday and Sunday nights (see picture of surface hoar from a north facing slope on Monday).

    (1/1/2024)

    Surface Hoar that formed during the clear weather on Saturday and Sunday night.

    Photo: Gabriel Coler

  • Persistent Slabs

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

    I have been having a particularly hard time including this Persistent Slab character in our problem list.  We have seen 0 avalanches on these weak layers, but observers have been finding some test results that are indicative of avalanche activity.  The message that I want to send is that avalanches are unlikely on these layers, but if I were considering riding a large, steep slope at the indicated aspect and elevation I would definitely do some digging to investigate these layers first.

    The two persistent weak layers we have been finding include: a layer of buried surface hoar which will likely be 30 cm down and a layer of facets directly beneath a crust down 40 cm.  The good old compression test has been my go to tool for finding and investigating these layers.

    As more snow piles up on these weak layers over the next week they could become more problematic.

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