Boletín de aludes

Southeast Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Thu
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche danger is rising due to heavy snowfall and wind loading.   Large natural avalanches are possible and human triggered slides are likely.  Instabilities will develop within the new snow and in weak layers that are buried up to several feet deep.  We've seen a string of notable human involvements with buried weak layers on the northern half of the compass this week:  Yesterday, a skier was briefly caught and carried in a slab avalanche. On Monday, a large slab avalanche was triggered on Schuylkill Ridge.  Over the weekend, a snowboarder was caught and partially buried when he triggered an avalanche from below the slope.  Conservative terrain choices are essential for safe travel today.  Instabilities will be smaller and easier to manage on southerly facing, wind-sheltered terrain.  

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2.5

    On the northern half of the compass, you can trigger a dangerous slab avalanche that breaks up to several feet thick on weak faceted snow buried last month.  Slabs can be triggered remotely from below or adjacent slopes.  Collapsing and cracking are clear signs of instability, although feedback on this problem is becoming more variable.  For example, a skier on Monday triggered a large slab avalanche on Schuylkill Ridge after reporting no signs of instability all day.  Use extra caution and choose more conservative terrain on slopes that face northwest to east.   

    This persistent slab caught and partially buried a snowboarder last weekend on a northeast aspect below treeline. The snowboarder triggered the avalanche from below the slope while he was hiking uphill.  

  • Storm Slabs

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

    Increasing winds and periods of intense snowfall later today will spur instabilities within the new snow.  Slabs will be larger and more sensitive in wind affected terrain, especially behind leeward features.  Monitor snowfall and wind drifting, and assess how well the new and recent snow is bonding on test slopes before riding in avalanche terrain.  On the northern half of the compass, a smaller storm slab can step down and trigger a larger persistent slab: avoiding steep terrain is the most reliable way to manage this complex setup.    

    An example of a storm slab avalanche that failed earlier this week.

Avalanche Discussion

Dangerous avalanche conditions are developing with a potent system moving into the region today.  Snowfall and winds will ramp up through the day and peak with intense snowfall rates sometime around sunset with the passage of a cold front.  The avalanche danger will ramp up accordingly.  

We've drawn a few differences between our two forecast zones today with the avalanche problems.  Persistent slabs are generally larger but more stubborn in the deeper snowpack of the Northwest Mountains, whereas they are a bit smaller but more reactive in the shallower Southeast Mountains.   Regardless of those two differences, your mindset should be the same: severe distrust of slopes stretching from West-northwest aspects to North around to East aspects.  This very large avalanche remotely triggered in the Aspen Zone yesterday should draw your attention to the potential size of human-triggered and natural avalanches today.   On southerly aspects, meltwater from last week's warmup drained deep into the snowpack and refroze into a thick crust, which has made triggering a persistent slab unlikely on those more sunbaked aspects.  

We are showing a higher likelihood for storm slab instabilities in the Northwest Mountains.  The snowbelt will be favored by today's snowfall, and will also get impacted by the late-day snow squall first, potentially before sunset.  Through most of the day, I expect storm slab instabilities to remain localized to drifted terrain at higher elevations.  Once heavy snowfall rates show up later today, we may see widespread storm slab instabilities develop across all of the terrain.   Stay away from drifted slopes today, and be prepared for changing conditions once snowfall rates intensify later this afternoon or this evening.   

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