Boletín de aludes

Gunnison

Crested Butte Avalanche Center
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Peligro de aludes

Fri
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Over the past few days, the continuous streak of large to very large natural and triggered avalanches has shown that the snowpack is struggling to recover from last weekend's massive loading event. Conservative terrain choices are paramount. Low-angle terrain and south to southwest aspects offer the safest options. Be careful of overhead hazards from remote trigger potential or the isolated threat of a natural release.  

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3.5

    Weak facets and collapsible crusts are widespread on the northern half of the compass and on some sunnier aspects at high elevations.  Recently formed slabs on top of these weak layers are 2 to 3 feet thick in wind-sheltered terrain They are easy to trigger in some shallower areas, and are becoming more stubborn on slopes with a deeper snowpack.  Slabs are thicker and harder in wind drifted terrain and can step down through older slabs to the ground.    Avalanches can break widely across multiple terrain features and be remotely triggered from flat terrain near or below steep slopes.  Feedback is variable on the problem; warning signs may not be obvious. The problem is less common on south and southwest aspects, and can be avoided on slope angles consistently less than about 30 degrees.  

    These destructive persistent slabs ran sometime in the past two days on Schuylkill Ridge.  

Avalanche Discussion

Good visibility on Sunday and Wednesday and many great public observations have helped us document a large dataset of avalanche activity since we were walloped by multiple feet of snow last weekend, followed by consistent westerly winds.  During the meat of the storm from February 14 to 15th, we saw widespread activity around the compass.  In the days that followed, storm instabilities settled out. Still, we have seen a continuous string of human-triggered and natural avalanches breaking on the persistent weak layers formed during our January drought, occasionally stepping down to early-season weak layers at higher elevations.  As the frequency of avalanches has declined since our blockbuster storm ended, slab connectivity and size have gone up.  Except for a few wind slabs, slab activity after the storm has quite neatly fit into a clear distribution: west, north, and east aspects at all elevations and higher elevation southeast aspects.   Highlighted by our persistent slab rose, these slopes had the weakest structures below our big storm: facets or facets capped by thinner, collapsible crusts.  Some drifted southeast-facing releases may have also failed on small facets above the crust, and there's some uncertainty about whether these same ingredients exist on a few high south or southwest aspects.

Similar to our holiday cycle, the snowpack in steep terrain significantly differs from the snowpack in low-angle terrain.  This season, we have hundreds of repeat offenders holding a weaker and shallower snowpack than flat terrain.  So, as you assess the snowpack, note that pit results or a lack of collapses or cracking may provide false-stable information.  The evidence is clear from all of the natural activity in the past few days from both of our forecast zones that the snowpack - one of our shallowest and weakest in recent memory (before the storm, of course) - is struggling to handle the burden of this week's snow and wind-loading, particularly on the problematic aspects highlighted above.  

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