Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Fri
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2 · Moderato
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1 · Debole
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger should be minimal for Thanksgiving, but you can still find an avalanche in select locations.  Navigate around steep terrain where you identify recent wind drifting. Slopes that receive strong sun could produce loose snow avalanches. Early season hazards still exist in many areas. 

Problemi valanghivi

  • Wind Slabs

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    • Limite del bosco
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    Probabilità
    Possible
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    1

    Pockets of reactive wind slab can be found even though they are isolated in distribution. One person triggered a small slab and took a short ride on Wednesday in the West North forecast zone. On the other hand, observers in many other areas have reported minimally wind-affected snow, even at upper elevations.

    While small and seemingly harmless, getting caught in a small wind slab could still result in getting pushed into a terrain trap or dragged across rocks, stumps, etc. Look for signs of previous wind loading like cornices, wind-scoured ridgelines, and thicker, stiffer drifts.  You are most likely to find wind slab along upper-elevation ridgelines, in complex terrain like gullies and couloirs, below cliff bands, or on steep, unsupported slopes.

    Assess stability before moving into steep terrain where you suspect wind slab, especially terrain with consequences in the runout below.  If you observe more wind than forecast, be prepared to find fresh, reactive slabs that will take a more conservative strategy to navigate safely

    Use small, wind-loaded features to test wind slab reactivity.

    Photo: Jason Speer - Baker Mountain Guides

Avalanche Discussion

The amount of sun on Thursday could vary widely across the West Central forecast zone. Significant loose snow avalanche activity is not expected, but you could still see rollerballs and small avalanches. You are most likely to see these below cliffs and steep treed terrain that sheds snow with warming. Avoid being on or directly under steep slopes where you observe signs of instability.

The biggest snowpack variable might be the amount of loose, dry snow on the ground. Some areas have 6” or less above a layer of rain-affected snow, while others have 12” or more. An increase in wind speed will drift this soft snow into fresh wind slabs. Significant warming will likely produce wet loose avalanches. The more fresh snow you find, the greater the avalanche danger when one of these weather factors eventually comes into play.

As usual, observations from West Central are limited. An NWAC forecaster in the Highway 2 corridor found a right-side-up snowpack with minimal instabilities on Monday (observation). There was evidence of previous wind transport along ridgelines.  Small rollerballs were observed on steep slopes in the freshly dampened, low-density surface snow. Lower elevations still harbored obstacles such as exposed or subtly buried stumps, rocks, and creeks.

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