Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

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

In sintesi

Take advantage of our unusually safe avalanche conditions before we get back into the storm track.  Consider the threat of small sluffs and rare lingering wind-drifted slabs before riding in consequential avalanche terrain. 

Problemi valanghivi

  • Persistent Slabs

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

    After below-average snowfall for the last three weeks, weak layers near the ground are dormant on most slopes. A northerly wind event on Christmas formed a newer generation of persistent slabs on leeward terrain features where hard, drifted slabs buried facets or faceted crusts in the upper snowpack. Those newer slabs have now also become stubborn or unreactive to triggering. The most concerning terrain features are where a recently formed hard slab is hanging on an unsupported slope such as a convexity, over a cliff band, or in extreme terrain.   When in doubt, move to softer or more wind-eroded snow.  

Avalanche Discussion

In yesterday's discussion, we took a zoomed-in look at local weather and avalanche activity patterns.  Today, let's zoom out to a regional scale.  The Mountain West has suffered through similar patterns: early season weak layers, persistent slab development with December storms, and most recently, unusually dry weather to close out December.  Our surrounding avalanche centers in Colorado, Utah, Wyoming, and Montana all have Low danger and are dealing with similar issues: the low likelihood threat of an old slab breaking in wind-drifted terrain, along with sluffing in the rotting snowpack.  There have only been a few slab avalanches reported around this entire Rocky Mountain Region in the past week, which highlights the low likelihood situation for triggering a slab avalanche right now.   Furthermore, the most recent slab avalanches look fairly similar in the terrain characteristics: heavily wind drifted, dense slabs (ex. Colorado, ex. Utah, ex. Wyoming).  The more common instability has been loose dry avalanches, which is symptomatic of our weakening and faceting snowpack.  In some parts of the West, facet sluffs are entraining the entire snowpack (ex. Aspen), and at least one person has been caught off guard by a deep gouger in Utah.  Fortunately, we haven't found that to be the issue here yet, but it's something we are monitoring for (Ex. Elk Creek, Ex. Happy Chutes).     

In the next week, the Mountain West will be coming off of a prolonged dry spell and enter back into the storm track.  This is often a recipe for accidents: powder-starved backcountry travelers interacting with loading onto the challenging persistent weak layer issues that develop from droughts.  Snowfall in the next few days looks to be fairly minor so I'm not expecting any significant changes in the short term.  With the storm track expected to return to the region by Sunday and into next week, conditions will be changing soon enough, so take advantage of the green light while we have it.  We may not see it again until spring. 

Regioni coperte