Bollettino valanghe

Southeast Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

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

In sintesi

Moderate westerly winds were observed to drift snow onto upper elevation slopes in the Southeast Mountains yesterday.  The continued loading will make recently drifted features the most concerning terrain.  Use caution and conservative decision making while traveling near wind-loaded slopes.  Sheltered terrain will offer safer recreation opportunities and a reduced likelihood of triggering a dangerous avalanche.

Problemi valanghivi

  • Persistent Slabs

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

    There are two flavors of persistent slabs that you can trigger today.  The problems are most dangerous on windloaded slopes where slabs are thicker. The youngest generation of persistent slabs is more widespread, on steep slopes where recent and windblown snow formed soft slabs over weak facets and faceted crusts in the upper snowpack.   The older generation involves stubborn hard slabs that could fail on weak layers near the ground - a more dangerous but more isolated problem.  Persistent slabs can be remotely triggered from below a steep slope or propagate widely across the terrain.  Shooting cracks and collapses are clear warning signs of this problem; however, persistent slabs are notorious for giving unreliable feedback.  For example, there were numerous tracks on the slope before a skier was nearly caught in the large avalanche on Schuylkill Ridge.  Give yourself a wide margin for error when assessing and managing persistent slabs.  

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    Yesterday, observers noted some transport in the Southeast Mountains.  With moderate to strong winds yesterday, expect wind slabs to have increased in size.  If you have good visibility today, they should be fairly easy to identify.  Look for and avoid smooth, rounded drifts below ridgelines and rollovers or in cross-loaded gulleys.  The snow will feel thicker and denser where it is wind-loaded.  You can avoid the problem by seeking out softer, wind-protected snow.  

    1/27: A shallow wind slab triggered on a wind drifted slope below treeline. Expect slabs like this to be thicker at higher elevations.

Avalanche Discussion

The loading of upper elevation terrain continued yesterday with moderate westerly winds.  Observers noted a relentless stream of wind-blown snow coming off high peaks and ridgelines.  That makes 6 consecutive days of loading due to snowfall or wind.  Yesterday, winds were generally moving at efficient loading speeds around 20 mph with some higher gusts.  To get a better sense of avalanche activity take a look at these two observations for yesterday (1,2); notice the sharpness of some crowns indicating the very recent timing of the failure.  Observations from just north of the CBAC forecast area in Marble also confirm the increased hazard on drifted slopes even at the near treeline elevation band (1,2). Winds backed off late yesterday and overnight, but the recent natural avalanche activity and wind-loading should grab your attention and give you pause before venturing onto dangerous drifted slopes.  

The most concerning terrain will be found in the Northwest Mountains where the most snow fell during the last storm and where winds recently transported the most snow.  Natural avalanche activity is expected to have largely run its course (so long as the winds do not pick up today and move more snow), but the likelihood of human-triggered avalanches remains elevated and concerning.  As you head towards the Southeast Mountains where less snow fell and less wind-drifting occurred the concern is a bit more subdued.  Uncertainty exists regarding how much snow was transported in the Cement and Brush Creek drainages as this terrain is difficult to view from afar.  Continue to use caution at the highest elevations where you see evidence of recent drifting in the Southeast Mountains.

Safer terrain options will be found on sheltered slopes free from recent drifting.  Even safer still will be sheltered slopes with 10 inches or less of storm snow from this past weekend.  Slopes less than 30 degrees without overhead hazards will always offer the safest recreation opportunities and the good news is, these slopes have great riding conditions at the moment.

  

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