Bollettino valanghe

Gunnison

Crested Butte Avalanche Center
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Pericolo valanghe

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

In sintesi

Danger! The threat of triggering a large and potentially unsurvivable avalanche is very real. On windloaded slopes, several destructive avalanches have released naturally in the past few days, and in wind sheltered terrain, remotely triggered slabs breaking 2 to 3 feet thick are the norm on all but southerly aspects. Give yourself a wide margin for error as we allow our snowpack to adjust from the major storm that doubled the snowpack on many steep slopes. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    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 and are easy to trigger in many areas.  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 southerly aspects where buried crusts are thicker, and can be avoided on slope angles consistently less than about 30 degrees.  

    On Tuesday, these three persistent slabs were triggered by skier from a single collapse on flat terrain.

  • Wind Slabs

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

    Westerly winds have been drifting snow for the past few days, forming several generations of wind slabs on leeward terrain features at higher elevations.  Winds are shifting to the northwest today and could find more transportable snow. As drifting continues, slabs become thicker, stiffer, and more stubborn.  They can break above you or step down and release a much larger persistent slab on some slopes.  To avoid the problem, seek out softer snow in wind-protected terrain or wind-eroded slopes.  Drifts are most common below leeward ridgelines and in crossloaded gullies: they will look smooth and rounded and feel denser and harder.

    A skier was caught and carried in this wind slab on Monday.  

Avalanche Discussion

Our snowpack is full of lemons. Seeking out the fun, stress-free riding in conservative terrain is the best way to make lemonade at the moment.  The steady pattern of human-triggered avalanches and continued natural avalanche activity paints a clear picture of dangerous conditions.

In West Brush Creek, Eric and I found ideal slab thicknesses for human triggering - with remotes from almost a thousand feet away, slides breaking in relatively tight trees, and sympathetic releases (see video).  Evan reported multiple releases from a remote trigger in Cement Creek.  This set of large avalanches on Snodgrass snapped some little trees sometime in the past few days.  Slabs are a bit thicker and provide less frequent feedback in the Northwest Mountains, though in many cases, weak layers are just as fragile.  Several flush cycles earlier this winter kept the snowpack unusually shallow and weak through our January dry spell.  It might take a faceplant, a trenching sled, or just crossing a shallower part of the slope near a tree or rock to bring down the whole slope.  This observation from near Marble (similar snowpack to our deep zone) highlights the sensitivity, along with several triggered slides over the weekend near Beckwith Pass and Ruby Dike.  

Steady wind drifting since the Cupid Crusher storm ended has kept naturals ongoing on leeward slopes at upper elevations.  The frequency of natural activity has significantly declined since the storm ended.  However, the scary part is that slides are growing increasingly destructive as slabs stiffen and thicken from the wind or gain enough midpack strength to fail on depth hoar layers at the ground.  Gothic Mountain hit the East River sometime in the past few days, Cement Mountain produced a massive crown that likely involved most of the snowpack. The Ruby Range has remained in the clouds and wind since we spotted a few big ones on Sunday like this monster on Oh-Be-Joyful. 

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