Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Sat
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Very dangerous avalanche conditions exist.  A warm and wet storm has deposited between 14 and 26 inches with another foot or more expected today.  The snowfall is very dense and contains an unusually large amount of water weight.  Natural avalanches are likely and human-triggered avalanches are very likely.  Expect avalanches to be more than large enough to bury a person and some avalanches may be unsurvivable and run long distances.  Travel in avalanche terrain is not recommended.  

Problemi valanghivi

  • Storm Slabs

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

    Storm totals range from 14 to 25 inches as of 5 am and contain a whopping 1.1 to 2.9 inches of water with another foot or more of snowfall today.  The storm snow is unusually dense and has already formed a cohesive slab.  Expect Storm Slabs to be very sensitive to the weight of a person today as new snow continues to pile up.

    An example of an avalanche earlier this season, that propagated widely, which gives a good representation of how far the current Storm Slab avalanche problem may propagate due to the cohesiveness of the slab.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    Weak layers can be found near the ground, in the middle of the snowpack (buried surface hoar), and some slopes that previously avalanched or sat shallow prior to the current storm are completely faceted.  With exceptionally dense and heavy storm snow resting above these weak layers, you can expect natural avalanche activity and a high likelihood of human-triggered avalanches on Friday.  Anticipate that you can remotely trigger a dangerous avalanche from below or adjacent terrain.  Avalanches can break wide and connect through terrain features particularly for areas that receive the most snowfall or where southwest winds have drifted snow into larger, thicker slabs on leeward terrain.  If you head into the mountains today, carefully manage overhead terrain as some avalanches may run a long distance and be destructive in size.

    This widely propagating persistent slab ran naturally on December 10th on Mt. Axtell that illustrates the wide propagation potential as well as the impressive destructive size you expect today.

Avalanche Discussion

The advertised potent winter storm has delivered on forecasted storm totals and water amounts yesterday and last night.  The storm snow will continue to pile up on Friday only adding to the already dangerous conditions.  Simply put, travel in or directly below avalanche terrain is not recommended today.

Storm totals are impressive with roughly 14 to 25 inches of snow in the past 24 hours, but the water content and snow density are highly abnormal for the Crested Butte area.  Schofield Pass Snotel site recorded nearly 3" of water since Thursday morning!  This heavy load, which will only stack up more today, will stress known weak layers in the snowpack.  Basal facets are widespread on the north half of the compass, surface hoar was buried a weak ago on shaded slopes, and terrain that previously avalanched is weak due to shallowness.  Additionally, some terrain very near town is shallow and very weak and will not tolerate much of a load (take a look at the video in the gallery below to see the weak snow on the hills immediately surrounding Crested Butte).  These factors combine to make natural and human-triggered avalanches nearly certain today.  On sunny slopes, the storm snow is often falling on crusts, some thick others thin.  The tremendous and rapid load will make even southerly-facing avalanche terrain a dangerous place today.

There is the potential for some avalanches to run long distances and even reach the valley floor.  If you venture into the mountains today with the mindset of avoiding avalanche terrain be certain that you are fully aware of slopes above you.  

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