Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

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

In sintesi

Rain often leads to avalanches.  Monday's weather forecast calls for continued rain and warming temperatures.  This means that avalanches will continue to be likely.  Despite our relatively shallow snow pack, Wet Slab avalanches could fail near the ground and be large enough to bury a rider.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Wet Slab avalanches occurr when rain and warm temperatures bring free water into the snow pack.  Rain adds more load to our snowpack and it also percolates down to  weak layers that maybe weren't quite weak enough to be problematic.    We have several weak layers in our snowpack right now:  previously cold dry powder from early in the storm, as well as facets that developed during the cold dry weather after Thanksgiving.  Today at 6,500 ft. these facets were failing with sudden test results 55 cm. below the surface (see accompanying video).

    Wet Slabs are  difficult to predict.  One critical factor is how deep water has moved in the snowpack.  This depth will obviously increase as steady rain continues, but it will vary over elevation as the snow line moves higher.  The forecast is calling for a decrease in rainfall, but with periods of rain and temperatures above freezing this is a hard problem to time.

  • Loose Wet

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

    As rain and warm temperatures melt the surface snow, Wet Loose avalanches are likely.  They should definitely be a secondary concern to the Wet Slab problem since they are significantly smaller.  Wet Slabs and Wet Loose avalanches can occurr together.

Avalanche Discussion

Today's heavy rain sure put a hurt on our snowpack, soaking the snow to at least treeline elevations.  At 6,500 ft. today there were large rain runnels.  Total height of snow at this elevation was 75 cm.  Beneath our latest storm snow I found 15-20 cm. of poorly developed facets and crusts.

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