Bollettino valanghe

Gunnison

Crested Butte Avalanche Center
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Pericolo valanghe

Thu
Alta quota
1 · Debole
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Northwest winds increased last night.  In wind affected terrain, watch for fresh drifts.  In wind sheltered terrain, loose snow avalanches are common on the northern half of the compass.   Either of these small issues will carry more serious consequences if you get pushed into a terrain trap such as cliffs, trees, or gullies.  

Problemi valanghivi

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Dry loose avalanches (sluffs) are a concern in wind-sheltered terrain on the north half of the compass.   Where the snow surface is weak and cohesionless, you can easily trigger sluffs that entrain the top 6" to 10" of loose snow on slopes steeper than 35 degrees. Ski cuts, moving across the fall-line while descending, or choosing lower-angled slopes are effective techniques to manage this problem. These point-release avalanches will accumulate more mass in long-running, steep terrain. Use caution above gullies where an avalanche can pile more deeply and above trees and cliffs where the consequences of getting caught in a small sluff will be magnified. 

    A great example of sluff management in terrain where a loose dry avalanche could be more problematic because it gets funneled down a gulley.  

Avalanche Discussion

Winds.  They're not helping the riding quality, but they are changing avalanche conditions.  Northwesterly winds increased to 25 mph, gusting into the 40's yesterday afternoon and overnight.  This means two changes: 

  1.  There's not much snow available for transport on northwest facing fetches anymore, but some drifting snow was observed yesterday mixing into near treeline elevations where the snow surfaces are softer and have more loose snow to pick up.  You may find a few more pockets of wind drifted snow out there today.  Any fresh slabs that formed will be on top of fragile surface facets, so they will be easy to trigger (see this ob of a very thin but widely propagating slab yesterday).  Look for smooth and dense lobes adjacent to rippled textures to identify the drifts. 
  2.  Where winds have worked the snow surface, they are decreasing the sensitivity of loose dry avalanches.  We trimmed above treeline a few days ago, and today, we trimmed west and northwest aspects near treeline from the loose dry distribution rose to account for fewer slopes in the northwest quadrant holding onto loose surface snow now.  The likelihood of triggering a loose snow avalanche near treeline is decreasing and may fit better with "possible" now, particularly in the Southeast Mountains where winds tend to mix into near treeline slopes a bit better.  Either way, your task is to take notice if snow surfaces are cohesionless and "sluffy", and manage for your sluff accordingly.  A forecaster on the Aspen side yesterday noted sluffs were running faster and further than expected. That's been the trend on this side of the Elks as well, a result of the strong inversions and diurnal temperature swings continuing to decay and weaken the snow surface where it is protected from winds.  

Regioni coperte