Bollettino valanghe

East Slopes North

Northwest 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 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You may still be able to trigger a slab avalanche on Wednesday. Identify steep slopes and features with recently drifted snow to avoid.  Watch for signs of instability such as shooting cracks and whumphing collapses. A weak layer of snow may exist between the recently wind transported snow and previous surfaces. 

Problemi valanghivi

  • Wind Slabs

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

    Strong winds and new snowfall left wind slabs scattered about in pockety distribution. Wind slabs may be triggered by surprise, and may propagate wider than anticipated. A layer of surface hoar was observed in many parts of the zone before the recent storm, so these slabs may continue to be reactive longer than you may think. Most wind slabs will be shallow, but expect the potential for larger avalanches as you ascend, where slabs may be thicker. This is also a good time to dig lots of quick pits, looking for a thin grey stripe of buried surface hoar underneath the recent snow.

    Identify recently wind loaded slopes and observe for cracking or whumphing as you travel. If you do find these signs of instability, avoid the obvious steep, wind loaded slopes, but also take into account cross-loaded and midslope features. Use surface textures and cornice formation as visual clues where slabs may be. Hollow sounding and firm or textured snow are other clues that wind transport has created slabs. 

    (11/26/2020) The textured snow surface in this photo demonstrates cross-loading along the sides of gullies. Cross-loading can be difficult to manage as you travel up and down terrain.

Avalanche Discussion

6-8" of snow fell with Monday's storm. On Tuesday, an observer noted small loose dry slides on steep shaded slopes where the new snow was sliding over firm surfaces. On Monday a natural wind slab release was observed above treeline as intense winds loaded start zones.  Wind slabs may be reactive and easy to trigger over a variety of pre-storm weak snow surfaces (11/30) including surface hoar and recycled powder (near surface facets).  Outside of new snow avalanche concerns, observers have identified a snowpack with a favorable hardness profile and good stability in the mid and lower snowpack. The snow depth in the area is generally 3.5ft to 5ft deep. 

Look for rollerballs or small loose avalanches in very steep terrain where unconsolidated snow escaped the wind. On steep south facing slopes, the sun may warm the snow enough to create small wet loose slides. In the shade, loose dry avalanches may carry momentum and entrain weakening snow surfaces. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

Regioni coperte