Bollettino valanghe

Central Cascades

Central Oregon 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

Wind slabs will likely build through the night and into Saturday. Where you find actively wind loading slopes or recently loaded terrain, slab avalanchs will be likely to trigger. Triggering slabs on a persistent weak layer will be possible in very specific terrain.

Problemi valanghivi

  • Wind Slabs

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

    New snow is coming in Friday night into Saturday and predominantly SW winds. Potential wind slab avalanches will start on the small side and build throughout the day. Watch out for where the wind is moving snow and evaluate lee slopes carefully before dropping in. Wind slab avalalnches will mostly be on the small side, but could be large in isolate pockets of terrain. Just 4" of new snow can translate to windslabs 12" deep or more. 

    Wind slabs will be most sensitive to triggering while they are actively being formed and while they are still new. Watch for signs of blowing snow, fresh cornices, pillow drifts, and wavy surface texture as signs that slopes are wind loaded. If you observe cracking in the wind drifted snow back off to more conservative terrain.

  • Persistent Slabs

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

    This problem is very specific in location and will not be found on all slopes with the aspects indicated above. Weak faceted snow and buried surface hoar have been reported at Tam Rim on NW, N, and NE slopes. Currently, the persistent weak layer is down about 8-12" and may be deeper in areas with significant wind drifted snow. There was avalanche activity reported from Tam on Thursday and it was largely associated with the weak faceted snow. The persistent slab problem could be in other cold shaded areas in addition to Tam Rim and hopefully we will get more information on this in the coming days. If ever there was motivation to dig in the snowpack and look for weak snow, this is the time. Presistent slabs tend to propagate further than typical wind and storm slabs and can run fast in steep terrain.

    This problem may be short lived or it may stick around for a while.  There have been no reports of a persistent slab problem in the Todd Lake/Tumalo side of the forecast zone.

Avalanche Discussion

Two avalanche problems; one is very typical of the maritime snowpack and one is less common. We don't see a lot of 'persistent' type weak layers but usually a few make an appearance each season. The weak faceted snow found at Tam could round out quickly, time will tell. In our neck of the woods, persistent weak layers do not usally persist for long.  

No avalanche activity was reported on Friday.

 

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