Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Fri
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
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In sintesi

An AVALANCHE WARNING is in effect.  Heavy snowfall and wind-loading the past three days formed cohesive slabs above fragile weak layers.  Yesterday, numerous natural and human-triggered avalanches occurred with a close call reported from Walrod Gulch in Cement Creek.  Light snowfall and wind-loading from westerly winds will continue today.  Human-triggered avalanches are very likely today.  You can remotely trigger avalanches from a distance and some slopes could release naturally due to wind-loading.  Travel in avalanche terrain is not recommended.  Avoid traveling on or beneath slopes steeper than 30 degrees.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1.5–3

    Natural and human-triggered slabs breaking several feet thick are very likely today.  2 to 3 feet of new snow and strong winds have formed touchy slabs on top of exceptionally fragile facets and faceted crusts.  The avalanches can be triggered from below steep slopes, they can propagate surprisingly wide distances, and they can fail spontaneously.  There was extensive evidence of this problem on Tuesday and Wednesday, and it will grow a bit larger in size on Thursday.  Choose slopes that are consistently less than about 30 degrees that don't connect to steeper terrain above you.  

    This slab failed on a collapsible crust and propagated 1500 feet wide.  

  • Storm Slabs

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

    With heavy snowfall and windloading today, avalanches breaking on layers within the storm snow are a common threat.  In most terrain, slabs breaking within the storm snow will immediately step down to release a persistent slab that fails on the dry spell weak layer a few feet down.  On south to southwest aspects, the step-down and unusual slab behavior is less likely, so you'll be managing for storm slabs running on crusts or on layers within the storm snow.   Cracking and heavy snowfall rates are red flags for this problem.

Avalanche Discussion

Intense snowfall rates yesterday produced numerous natural and remote human-triggered avalanches.  Large, dangerous avalanches were observed from both forecast zones including a report of a natural avalanche in Walrod Gulch out Cement Creek nearly hitting a person walking a dog.  Take a look through our observation page or look through the media gallery below to see evidence of the dangerous conditions.  A couple of good examples of current conditions can be found in this observation from Mount Axtel and this one documenting natural avalanches in Climax Chutes.  Dangerous avalanches were remotely triggered in these observations from Mount Emmons, Coney's, and near Elkton.  Storm snow has settled into 2 to 3 foot thick slabs across much of the terrain in both forecast zones.

For today, the danger rating remains HIGH even though snowfall rates are diminishing throughout the day.  Slopes that continue to endure wind-loading from westerly winds will be suspect for natural avalanche activity.  Due to the sensitive nature of the weak layer that formed during the prolonged dry spell, human-triggered avalanches remain very likely today.  The biggest difference between today and yesterday is a decrease in natural avalanche activity, particularly in sheltered terrain.  It is less dangerous today, BUT conditions still fit into the HIGH rating.  

If you choose to venture into the mountains today, you need to identify and avoid avalanche terrain to effectively manage the current conditions.  This includes being aware of overhead hazards and not wandering into the runout zones of large avalanche paths.  Place a large buffer between the terrain you are in and any adjacent or nearby avalanche terrain.  Even though the storm is ending today, avalanche conditions remain very dangerous and require your full attention. 

 

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