Bollettino valanghe

Northwest 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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In sintesi

It's a great day to hunt for wind-protected snow in the trees, where snow quality is better and avalanche conditions are generally safe.  Extreme winds will create difficult travel and potentially dangerous avalanche conditions on leeward terrain at higher elevations.  Large natural avalanches are possible on wind-loaded slopes, and they'll be sensitive to the weight of skiers and riders. Watch for wind slabs forming on open or exposed below treeline slopes as well.  Blowing snow and thick-feeling drifts are signs of trouble.  

Problemi valanghivi

  • Wind Slabs

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

    Strong to extreme winds overnight and today are transporting snow into thick, reactive drifts in leeward terrain.   Wind slabs will be most common near and above treeline, but can also form on open slopes below treeline.  Blowing snow, thick-feeling drifts, and cracking in the snow are warning signs.  Wind slabs are most likely to be found below ridgelines, in cross-loaded gullies, or behind rollovers or tree fences.   You can avoid the problem in wind-protected or wind-eroded slopes.   

    An example of a large wind slab that ran during last week's extreme wind event.  

Avalanche Discussion

Strong to extreme winds arrived overnight and will continue through the day.  There's a significant amount of snow available for wind transport in the Northwest Mountains, where Friday's storm delivered over a foot of low-density snow to the alpine.  Although recent storm totals were less in the Southeast Mountains, there's still a decent amount of soft snow in the terrain for extreme winds to work with.  Because today's danger is driven exclusively by wind loading, there will be a lot of slope-to-slope variability depending on how the wind moves through the landscape.  Some terrain will be heavily eroded, some terrain will be heavily loaded, and some terrain will remain untouched by the wind.  With a careful eye for wind drifting patterns, you can avoid the most dangerous slopes and enjoy a safe day out there.  If you want to keep it simple and keep your beautiful hairstyle in place, seek out wind-protected terrain.  If you're trying to punish your friends, take them for a scenic ridgeline walk.  

With almost every wind event in the past month, we've observed one or a few persistent slabs release on windloaded slopes in the Southeast Mountains.  Yesterday evening, a resident in Conundrum Creek (on the Aspen side) reported a rumbling avalanche and a large powder cloud reaching the valley floor a few hours after wind transport began (photo in gallery below). That's a notable indication that weak layers are again under distress.  The problem is most concerning near and above treeline in the Southeast Mountains, though isolated exceptions could exist elsewhere.  

Winds will decrease tomorrow and snow transport should wind down overnight; thus the peak of instability will be today.  There's always some uncertainty during unusual wind events as to where and how extensive wind loading is, versus blowing into the atmosphere.  We'll be monitoring wind loading patterns and sensitivity trends today to help re-assess tomorrow's danger ratings.  

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