Boletín de aludes

Southeast Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Thu
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Although the odds of triggering an avalanche are a bit lower than last weekend, the consequences remain deadly.   The most worrisome slopes have variable or thin snow depths and face the north half of the compass.   Cooler temperatures should improve stability on southerly aspects today unless surface crusts melt off.   A recent string of local close calls and almost daily accidents around the state highlight challenging conditions that require careful snowpack evaluation and cautious route finding. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    Weak facets and collapsible crusts are widespread on the northern half of the compass and on some sunnier aspects at high elevations.  Slabs on top of these weak layers average 2 to 3 feet thick in wind-sheltered terrain. Slabs are thicker and harder in wind drifted terrain and can step down through older slabs to the ground.    This problem is becoming more stubborn to triggers, often requiring a thin spot on the slope, such as near buried rocks, trees, or where slabs thin from wind effects. Avalanches can break widely across multiple terrain features and be remotely triggered from flat terrain near or below steep slopes without warning signs. The problem is less likely on southerly aspects due to recent melwater refreezing in the snowpack, and can be avoided on slope angles consistently less than about 30 degrees.  

    These destructive persistent slabs released on Wednesday 2/19.  These exemplify the potential size avalanche you could trigger on large, drifted slopes. 

Avalanche Discussion

Our poor little snowpack has been put through the ringer since Valentine's Day.   First, multiple feet of snow, then sustained wind drifting, and most recently, warm temperatures have all caused large natural slab activity paired with large human-triggered slides.  A similar pattern has occurred across the entire state, and the number of close calls and deadly accidents is frightening.   Cooler temperatures should finally pause natural activity today and improve stability on southerly aspects.  The best snow quality is guarded by the most worrisome aspects for triggering a persistent slab.  Human triggering a large and deadly slide remains a concern in both forecast zones.  There are more slopes of concern with thinner slabs and weaker snowpacks in the shallower Southeast Mountains, where we've consistently found more unstable pit results, more remote triggers, and more signs of instability in the past week.  With lower likelihood but high consequence problems across our entire region, both zones are straddling the fence for danger rating. The Southeast Mountains landed on the Considerable side, and the Northwest Mountains are on the Moderate side today.

Over the past several days of warm weather, we saw a few slabs that appeared to release from meltwater weakening buried facets and depth hoar layers on sunbaked aspects (Ex. Red Ridge).  Wet avalanche issues are expected to pause today under colder temperatures and crusty surfaces.  They will become more threatening in the next few days as temperatures soar to the hottest of the season.  Expect wet slabs on the problem list tomorrow, perhaps with a few sightings of seasonally confused migratory birds or camels.  If you plan to travel on or below steep slopes on the southern half of the compass, you will find safer travel earlier in the day while the snow surface is frozen or just starting to thaw.  This video describes the situation on Mt. Emmons, and this video looks at the crown from a close call last weekend in Elk Basin.  It's not bomb-proof corn season yet, but surface crusts will help reduce the odds of triggering a slab - the thicker the better.    

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