Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Upper elevations will get around a foot of snow overnight, and it's likely that you could trigger an avalanche in the new snow layer. Travel on steep slopes as you ascend to higher elevations is not recommended, and the snowpack grows deeper than about 6". Lower elevations will mainly receive rain and the snowpack will probably be soft and punchy. 

Problemi valanghivi

  • Storm Slabs

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

    A foot of overnight snow means an increase in avalanche danger. Human-triggered avalanches are likely at upper elevations, where most of the precipitation will fall as snow. At mid elevations is less snow and lower avalanche danger. In areas more than about 6" of snow, avalanches could occur with a human trigger on steep slopes until the snow has had time to settle. Danger may be higher at the very start of the day, but stability is expected to improve as the snow settles.

    Snowlines wavered in the mid-elevation band for much of the storm. There probably won't be much snow at your starting elevation, but expect amounts to increase quickly as you make your way to upper elevations. Danger will increase as new snow depths increase. There is uncertainty regarding new snow amounts and how it will react at upper elevations. If you make it up there, be prepared to evaluate conditions for yourself. 

    The storm occurred with moderate to strong wind, so this new snow avalanche problem will probably be more reactive in wind-loaded areas. During your outing, stay on small terrain before you head to any larger slopes. Evaluate the bond between the new snow layer and the surface beneath. Determine whether there are any weaknesses within the new snow layer, especially if it is wind-affected. Steer around slopes steeper than 30° where there is more than about 6" of snow present on the surfaces. 

    Example: A human triggered slab avalanche similar to what you may encounter on Monday. 

    Photo: Irene Henninger

Avalanche Discussion

I traveled to 5500' in the Highway 2 corridor of the West Central zone on Sunday. I found a rather bleak snowpack until about 4500', where all of a sudden there was more snow and the weather was surprisingly winterlike. The snowpack was around 3 feet deep above 5000ft, and there was 6" of wind-affected snow above a stout melt freeze crust. This crust capped a variety of moist layers and crusts all the way to the ground. We don't suspect avalanches will happen beneath the new snow layers. 

At lower elevations, the snowpack will be wet, and you'll probably sink to the ground after the overnight rain. There's a very small chance small wet snow avalanches may run in the saturated snowpack. As is the trend for this year, beware of early-season hazards like shallowly buried rocks and roots, and open creeks. Don't forget there's a solid crust beneath new snow layers in most areas, which may be slick in places. We hope you enjoy the snow that does exist, and happy holidays from the NWAC team!

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