Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Avalanches will be possible at upper elevations where the wind has blown our most recent snow onto North and East slopes.  Last week, a large artificially triggered Wind Slab stepped down to older weak layers in the snowpack and the resulting avalanche was very large.  It is unlikely that backcountry travelers will encounter avalanches on these deeper layers, but we can increase our margin of safety by avoiding big, steep, slopes that may be Wind Loaded.

Problemi valanghivi

  • Wind Slabs

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

    Although it was storming all day on Sunday, the snow didn't really pile up at our sno-parks because it would switch back and forth with periods of rain.  It was likely a different story at higher elevations.  At near treeline elevations, the wind was doing a good job of moving snow.  Remember that wind deposited snow can be 3-5 times as deep as the snow that's fallen in open glades and meadows.  For elevations below 8000 feet the previous snow surface was a rain crust, so it shouldn't be too hard to figure out how deep the newly deposited snow is.

    While very large avalanches remain unlikely, your best chance of triggering one is by triggering a large Wind Slab that could then step down to the deeper layers.  I know I will be a little more conservative when it comes to engaging with big, steep slopes with this knowledge.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–3

    This Deep Persistent Slab has been on our problem list since last Thursday when Mt Bachelor patrol intentionally triggered a Wind Slab which stepped down to these deeper layers.  In this case, the weak layers were weak snow beneath the December 7 rain crust (now typically buried 80-120 cm) and also beneath the November 22 crust.  I have been digging down and looking at these layers for the last week.  I haven't been able to identify any persistent snow grains, and snowpack tests have not yielded results indicative of avalanches.

    My strategy is to avoid steep wind loaded terrain on big alpine faces; particularly North and East slopes, where I might trigger a Wind Slab that could similarly activate these layers.

Regioni coperte