Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Expect an increase in avalanche danger as a storm deposits a foot or more of snow, accompanied by wind, on Saturday night. Avoid thicker deposits of snow, and steer clear of them on steep slopes, especially if you see shooting cracks or hear and feel whumphing as you travel. 

Problemi valanghivi

  • Storm Slabs

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

    It is likely that you can trigger a slab avalanche on Sunday. Areas where wind deposited new snow into thicker drifts have a higher chances of producing an avalanche, however, enough snow will fall that it may avalanche even without large amounts of wind redistribution. Wind deposits tend to develop along ridgelines, around outcroppings, or in gullies. Any time you see bullseye clues such as recent avalanches, cracking, or whumphing there is a strong indication that you could trigger an avalanche. Other signs are recent snowfalls and wind, like what happened Saturday night. This is an obvious reminder to travel carefully on Sunday. 

    Steer clear of slopes steeper than 35 degrees if you find any thicker-feeling slabs or other clues that an avalanche could occur. Avalanche danger is expected to increase as you gain elevation, where more snow and wind-affected surfaces, and less information, exists. 

    (11/23/2020)

    Large cracks shooting out from your feet or snowmobile are indicators of a weak snowpack. Avoid steep slopes if this occurs. 

Avalanche Discussion

Minimal preexisting snow was present in below treeline areas, although a foot or more of snow is expected to fall even to lower elevations Saturday night. Isolated lower elevation locations which already held enough snow to form a smooth surface, or low shrub/grassy surfaces, are probably the only areas where smaller avalanches might occur below treeline on Sunday.

A snowpack of 2-3 feet sat under high pressure from Nov 8 - Nov 21. Weak, faceted crystals formed in shady areas. Meanwhile, hard, sun-affected surfaces developed on south-facing slopes. Upper elevation treeless terrain was buffeted with wind from all directions, so fewer pockets of weak snow developed on shady aspects here.  Isolated, shady and sheltered areas could still harbor weak snow, but we have limited information about its presence at the time. 

Despite this last storm,  it's still early season, and the snowpack is shallow. Lots of early-season hazards exist such as shallowly buried trees, rocks, and other obstacles. In terms of our snowpack, we're still gathering information about what's out there on the ground, so this forecast comes with a fair amount of uncertainty with limited information as a starting point. If you make it out on Sunday, don't hesitate to submit an observation. Information about any avalanches that you saw or triggered, thicknesses of new snow, or the entire snowpack depth in more areas is incredibly helpful for us. 

 

Regioni coperte