Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Sat
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You will find generally safe avalanche conditions in the Northwest Mountains.  Triggering a Loose Dry avalanche on shady, wind-protected slopes is slowly becoming more common as cold air temperatures weaken the snow surface.  This problem requires relatively steep terrain, 37 degrees or greater.  Ski cuts are a useful tool to get a feel for how the snow will behave once you push on it.  Use care to prevent a small loose avalanche from pushing you into trees, rocks, or off cliffs.

Problemas de aludes

  • Loose Dry

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1

    On very steep terrain sheltered from the sun and wind, you can easily trigger sluffs where the snow surface is loose and cohesionless.  Several skier-triggered sluffs on Tuesday in the Southeast Mountains highlight how these avalanches may have the potential to entrain the entire snowpack on some slopes.  The terrain in the Northwest Mountains is less likely to produce avalanches that entrain the full snowpack as compared to terrain in the Southeast Mountains closer to Crested Butte.  Be cautious descending confined gullies or in terrain where a loose avalanche could push you into trees or rocks.   You've found the problem if you find yourself sinking past your boot tops in loose, sugary snow.  Avoid trouble by moving to terrain less than 35 degrees or by moving to a sunny aspect.

Avalanche Discussion

Atmospheric conditions are slowly driving changes within the snowpack.  Cold and clear nights are weakening snow surfaces and on some terrain the entire snowpack.  Shady, protected terrain with a shallow snowpack, less than around 20 inches, is losing most of its strength and cohesion.  Slopes where you find weak, cohesionless snow are the most concerning for triggering a Loose Dry avalanche that gouges to the ground and entrains the full snowpack.  Check out Zach's video from a few days ago in the Happy Chutes area (observation here) on Mount Emmons for a great description of this terrain and some footage of how this type of avalanche behaves.  Lower elevation terrain, slopes close to town, and features that sit below the inversion level are the most concerning for producing Loose Dry avalanches that entrain most of the season's snowpack.  This snowpack setup is more common in the Southeast Mountains thus the reason for the increased danger rating of MODERATE.   As you travel further away from town or to higher elevations or to terrain with a deeper snowpack, like in the Northwest Mountains, you can find 6 to 8 inches of weak snow near the surface with denser snow below.  In these areas, Loose Dry avalanches will entrain only the weak surface snow and remain on the smaller side.  Take a look at recent forecaster observations from Mount Axtel or Purple Palace for a better picture of the problem where it is less concerning yet still exists.   To manage this problem you have a few effective options.  First, for locations where you find a cohesionless snowpack less than about 20 inches, it would be best to just avoid terrain steeper than about 35 degrees.  You will struggle to make turns and will likely be banging off the ground constantly.  Ski cutting will also work to remove some of the avalanche hazard, but you are likely to clean out all of the snow and have nothing to slide on.  For areas where you find supportive snow beneath the weak surface, you can choose lower angled slopes, less than about 35 degrees or ski cut to remove some of the cohesionless surface snow prior to descending.  Avalanches are anticipated to remain small, but you should consider the consequences of getting pushed into trees, off cliffs, or into a gully.  Slopes affected by the wind or sunny aspects will offer terrain choices where Loose Dry avalanches are not a problem.    

This Friday is CBAC's Virtual Avalanche Awareness Night!  The event includes avalanche talks, drive-through food and swag, an awesome gear raffle, and an "Ask a Forecaster" panel -  all broadcast live from the Center for the Arts with your favorite wacky host, Than Acuff.   Tune in on our YouTube channel from 6 to 8 p.m on Friday.  

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