Bollettino valanghe

Gunnison

Crested Butte Avalanche Center
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Pericolo valanghe

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

In sintesi

Though the threat has become increasingly rare, triggering an old wind-drifted slab remains the most consequential concern at higher elevations or on wind-exposed below treeline slopes. In wind-protected terrain, stay alert for dry loose avalanches on steep slopes where the snowpack is shallow and weak. These aren't the friendly, harmless new snow sluffs, but the mean, gouging facet sluffs that can catch you off guard or push you into trees and gullies.    

Problemi valanghivi

  • Persistent Slabs

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

    Slabs up to several feet thick are becoming increasingly isolated and difficult to trigger but remain a concern on a few previously wind-drifted slopes.  You are unlikely to see signs of instability before triggering an avalanche that breaks on old weak layers.  The most concerning terrain features are where old, drifted slabs are thin near their margins, convexities, or rocky areas. You can reliably avoid the problem on slope angles less than 30 degrees without steeper slopes above you, and most wind-protected terrain lacks the problem.  

    This avalanche was triggered by a backcountry rider on 1/26 outside our forecast area near Ashcroft. This is a good illustration of the wind forming a slab below a midslope roll. 

    Photo courtesy CAIC. 

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    You can easily trigger gouging  "facet sluffs" on some very steep (~40° ) slopes that are protected from the sun and wind.  You're most likely to encounter the problem in start zones that have avalanched multiple times this season and have an unusually shallow and weak snowpack (<50 cm).  These avalanches release predictably and start small, but can grow to harmful sizes in long relief or if they push you into trees or gullies.  Use defensive or off-fall-line riding techniques to manage the problem, or move to lower slope angles to avoid the problem.  

    A debris pile from loose dry avalanches accumulating in a gully below the Climax Chutes. 

Avalanche Discussion

The past two weeks of dry, cold weather have caused most slab avalanche concerns to grow dormant.  Bouts of wind drifting since our last snowfall events have kept the threat alive on a few favored slopes.  Identifying and avoiding slopes that effectively collect drifting snow from various wind directions remains the most reliable strategy for managing the unlikely - but not impossible - threat of triggering a large slab avalanche.   Valley winds in the past week have caused relatively shallow but more sensitive drifts to form in some locations below treeline, evidenced by several triggered wind slabs on Wednesday and reports of shooting cracks in recent drifts yesterday -both likely the result of midweek east winds that formed tender wind slabs over the well-developed facets that are widespread around our region.

The dry weather continues to promote faceting within the snowpack, causing ongoing dry loose avalanche concerns. The previous east winds may have affected the snow surface enough to reduce the problem on some slopes, while others remain problematic.  The most recent evidence comes from the Marble side, where a forecaster triggered numerous facet sluffs, one of which grew large in size on a long-running terrain feature.  

Conditions could change over the next 36 hours, depending on how much it snows.  Monitor for fresh slab formation if snow totals exceed our forecast. It won't take much to create new problems over our fragile snowpack.  Check out our latest weekly summary or video recap for more insight into our current snowpack setup.  

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