Bollettino valanghe

Gunnison

Crested Butte Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

🔥Another day in the furnace following our weakest refreeze so far.  Expect dangerous avalanche conditions to develop earlier in the day with our ongoing wet avalanche cycle.   The destructive wet slab problem will probably rear its ugly head again today after a couple of large slides ran yesterday in Climax and Whetstone.   There are options to seek refuge from wet avalanches on high north, but the threat of triggering a large slab avalanche breaking on deeper weak layers remains.  

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Several wet slabs failed yesterday as buried weak layers became saturated.  This is a difficult problem to assess or predict. You can reduce your risk by traveling early while the upper snowpack is frozen.  Weak facets a couple of feet deep and depth hoar at the bottom of the snowpack are getting flooded for the first time this season on some easterly and westerly aspects.  Steep slopes below rocky terrain tend to be the most active for wet slab activity.  There is typically not enough meltwater into the snowpack on northerly aspects to cause wet slabs this time of year, though exceptions could occur.

    A destructive wet slab ran yesterday in Climax Chutes on an east aspect near treeline.  

  • Loose Wet

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

    Wet loose avalanches are running naturally or are easy to trigger on almost all aspects and elevations once the top layers of the snowpack get wet.  Most are relatively small, while some gain volume in longer terrain or gouge deeper into the snowpack and grow large and dangerous in size.  Wet avalanches will first develop on steep easterly facing slopes this morning, then move to southerly, then westerly aspects following the sun.  Travel early while the snow surface is frozen or just starting to soften to avoid the problem.   Pinwheels, rollerballs, and natural wet activity are signs of decreasing stability.   Move to lower angle slopes, smaller terrain, or colder aspects once this happens.  

    A wet loose avalanche that started below a steep rock band and gained volume in long, steep terrain

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    In the past two weeks, numerous large to very large slab avalanches broke on weak layers in the upper snowpack and near the ground.  Feedback on the problem is variable and infrequent. Warming snow surfaces may cause the problem to become more sensitive. These issues are most concerning on wind-loaded terrain on colder, shadier aspects highlighted by the persistent slab rose.  Avoid steep, wind-loaded slopes and wind-affected terrain with variable snow depths to reduce your risk.   Persistent slab instabilities are more isolated below treeline; stay alert on very steep or unusually shallow slopes. Southerly aspects lack the problem.  

    A large persistent slab on Gothic triggered by a shallower wet avalanche on 3/25.

Avalanche Discussion

Observers yesterday reported large wet slabs in Climax and Whetstone on east aspects up to 11,500', and on higher southeast aspects on the Aspen side.   A similar pattern is expected today, with the problem potentially expanding to higher elevations and increasing in size as meltwater continues moving into the snowpack.  West aspects can mirror the wet patterns of east-facing terrain, so they're also on the most suspect list.  A weaker refreeze last night could contribute to an increasing frequency of wet slabs today.  Wet slab forecasting involves significant uncertainty. 

If you're seeking that window of improved stability while surfaces are frozen in the morning, expect it to end early.  Irwin's observation yesterday can serve as a reference point. Today will be worse due to some overnight cloud cover and overnight lows that were a few degrees warmer.  It'll be tough to stay ahead of the thaw on the east half of the compass this morning; you can buy yourself some extra time with terrain choices on the west half of the compass.  Due north has stayed dry so far; some greenhouse warming from clouds today might spoil that at mid to low elevations.  

Looking ahead, natural wet avalanche activity tends to decrease after the peak of warming has passed. However, we will still have to contend with wet problems tomorrow following another mediocre refreeze tonight.  A solid refreeze may be delayed with incoming snowfall and cloud cover on Friday night helping to insulate the snowpack.  

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