Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Wed
Alta montaña
2 · Moderado
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Numerous large wet avalanches ran on Monday, and it gets even hotter on Tuesday.   The avalanche danger will rise to Considerable as surface freezes deteriorate into dangerous wet snow.   In some areas, wet avalanches are involving the entire season's snowpack, producing deadly piles of cement-like debris.  Large cornices are more likely to fall during the peak of our warmup.   Start and finish your day early, and move to colder aspects and simpler terrain before the snowpack loses strength.  

Problemas de aludes

  • Wet Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–3

    Numerous large wet slabs have released since Monday on the aspects highlighted above, producing dangerous amounts of wet debris.  This pattern is expected to worsen on Tuesday and could expand to higher elevations or produce even larger slides.   Because the timing and amount of meltwater draining into buried weak layers vary significantly from slope to slope, there is a high amount of variability and uncertainty in predicting Wet Slabs. You can reduce your risk by traveling early while the upper snowpack is frozen solid and supports your weight, or moving to north aspects where there is currently less meltwater.  

    4/9:  A large Wet Slab avalanche ran naturally on the east-facing side of Gibson Ridge.

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Wet Loose avalanches have been occurring on all but the highest, coldest slopes.  At mid and lower elevations, they are gouging through significant amounts of saturated snow producing large and dangerous debris piles.   Frozen snow surfaces early in the morning will make for safe travel, but stability will quickly deteriorate from east to south to west slopes throughout the day and will involve some northerly terrain as well.  Time your travel while the snow surface is supportive and just starting to soften.  You're too late if you are sinking past your ankles or if you see rollerballs, pinwheels, or natural activity.  You can avoid the problem on lower slope angles or aspects that are still in the shade.

    4/10: Large, gouging wet loose avalanches like this are occurring at mid and low elevations.  

  • Cornices

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–3

    Large, overhanging cornices continue to fall on a daily basis under our current warming trend.   Some are capable of triggering destructive slab avalanches, while others are trundling down slope entraining large amounts of snow with car-sized chunks of cornice debris.  Limit your exposure on slopes with large cornices above, and give them a wide berth if you are traveling along corniced ridgelines.  

    A recent cornice fall in Redwell Basin.  Minimize your exposure to terrain like this.  

Avalanche Discussion

We are near the peak of our first major warmup and wet avalanche cycle on Tuesday.  Evidence abounds on our observations page or gallery below of dangerous wet avalanche conditions.  These aren't manageable wet sluffs: they are deeply gouging concrete mixers that are snapping trees or slabs that are breaking widely.    The largest and most dangerous wet activity thus far has been at lower elevations or in shallower/rockier terrain at mid-elevations, where we are seeing full-depth wet loose avalanches and wet slabs breaking several feet thick.    Our warmest night yet and warmest day yet will only exacerbate conditions, and we could see this type of activity expanding to deeper snowpacks or higher elevations.  The dust layer is surfacing across most of our forecast area and accelerates melt because of its lower albedo than snow.    Thus, expect conditions to destabilize faster than usual.  

With clear skies overnight and temperatures dropping to just below freezing, there will be a sufficient surface freeze to allow safer travel early in the morning.  That stability will vanish first on easterly aspects, then south, then west.  Have an exit strategy so that you are off and out from under steep terrain before it gets too hot.  High northerly aspects haven't seen the meltwater production to cause larger wet avalanches; some northerly slopes are just starting to get wet and could produce shallow wet sluffs.  Cornices can fall at any time of day, so continue to manage those overhead hazards as well.  If you aren't skilled at recognizing and managing wet instabilities, it's a great day to go for a bike ride or soak up Vitamin C on your deck (provided there's no roof avalanche hazard above you).  This is not your typical spring day in the backcountry.  

* In response to the warning trend this week, the CBAC is issuing avalanche forecasts around 7:30 p.m. describing conditions for the following day.  This allows backcountry travelers the ability to plan the night before and not need to wait until forecasts are issued in the morning.*

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