Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche conditions remain tricky, with signs of instability like cracking and collapsing becoming infrequent, but the consequences of a triggered avalanche remain severe. The worst snowpacks can be found in the northern half of the compass and in some high-elevation southerly terrain.  The unpredictable nature and dangerous size of avalanches can be managed through conservative terrain selection.  Stick to mellower slope angles without steep terrain directly above.  Mid and low-elevation southerly slopes offer notably less slab avalanche risk.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Slabs over buried weak layers 1.5 to 3.5 feet thick vary from stubborn to reactive under the weight of humans. These slabs are stiff and often do not show obvious warning signs before avalanches are triggered. The north half of the compass has the most fragile weak layers buried in the middle and bottom of the snowpack and is most likely to produce remote-triggered, widely propagating, and destructive avalanches from steep or adjacent flat terrain (see several videos illustrating this).  Some higher-elevation southerly terrain also harbors problematic structures.  Manage today's persistent slab problem by choosing lower-angle and more conservative terrain without steeper overhead hazards on the aspects highlighted above.

     

    A pair of large persistent slabs below Scarp Ridge, which likely ran during increased winds on Tuesday.  

    Photo: Irwin Guides

Avalanche Discussion

The avalanche hazard has been on a slow decline since the major loading event around February 18-20th, but conditions remain tricky.  Signs of instability (cracking and collapsing) have become less frequent, particularly in the Northwest Mountains.  However, a trickle of avalanche activity over the past week indicates that trouble waits on some slopes, albeit quietly.  On Thursday, observers remotely triggered an avalanche in West Brush Creek from hundreds of feet away on a northerly slope below treeline.  A group on Leahy Peak, near Aschcroft, remotely triggered a large avalanche on a southeast feature above treeline (This avalanche is outside the CBAC forecast area, but has a very similar snowpack to the Southeast Mountains). Further from the CBAC forecast area, but no less indicative of the hazard locally, a large avalanche was remotely triggered on the north face of Battleship in the northern San Juan Mountains.

The lack of signs of instability makes conditions feel safer than they are.  The dense slabs, around 2 to 3 feet thick, prevent frequent signs of instability, but problematic weak layers persist.  Recent snowpack tests from Elkton and Snodgrass (ob 1, ob 2) illustrate the issue.  Gauging the sensitivity of the problem or identifying where you might find a trigger point is a challenging, if not impossible, task, but understanding the severity of an avalanche is not.  A large portion of documented avalanches over the past two weeks are big enough to bury, injure, and kill a person.  Some would have been unsurvivable.   

Southerly terrain offers a much lower risk of slab avalanche except for some high elevation southeast slopes or as southwest slopes transition to westerly aspects.  The sunshine on Saturday offered nice riding conditions on southerly terrain, but increased cloud cover on Sunday may hamper the softening on many sunny slopes.  You may be able to find creamy surfaces on lower-elevation southern terrain due to warm temperatures and periodic sunshine.

Regioni coperte