Boletín de aludes

Southeast Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Snowfall started last night and may deliver up to 6 inches.  Strong winds drifted snow to leeward terrain features.  You can trigger an avalanche in the recently drifted snow.  An avalanche in freshly drifted snow could step down to weak layers a few feet deeper.  Use caution around drifted terrain particularly if you see cracking in the new snow.  Selecting sheltered terrain will reduce the chance for you to trigger an avalanche.  Although unlikely, portions of the Southeast Mountains with depths around 3 to 5 feet could still produce avalanches breaking near the ground on shaded aspects.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Strong winds began yesterday afternoon out of the southwest transporting old snow and new snow overnight.  Winds are forecasted to shift to the northwest this morning which will change the loading patterns.  Avalanche activity in recently drifted snow is expected to remain smaller in size but could grow close to large sizes if the storm overproduces or on continuously long slopes.  Fresh Wind Slabs are expected to be smaller in the Southeast Mountains as less snowfall is forecasted.  Cracking in the new snow and feeling an increase in stiffness is a clear sign you have found a freshly drifted slab.  The most likely places to encounter a Wind Slab will be along the leeward side of ridgelines, below cornices, beneath abrupt terrain breaks, and cross-loaded windward features.

    An example of a Wind Slab from two weeks ago that formed on the leeward side of an alpine ridgeline.  Similar conditions may exist today.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–3

    In the Southeast Mountains, there are several faceted weak layers in the snowpack that have produced avalanches over the past week.  The most recent storms buried facets and faceted crusts up to a couple of feet thick, and there is a lurking layer of depth hoar near the ground.  Avalanches breaking near the ground are most concerning in terrain with an unusually shallow snowpack between 3 to 5 feet deep.   Instabilities in the upper snowpack are more common in wind-drifted terrain.  Use small, steep slopes and/or stability tests to assess for instabilities in the upper snowpack.  You can generally avoid the problem by staying on slopes consistently less than about 35 degrees.   

    These avalanches on Snodgrass appear to be remotely triggered on 2/1.  They failed on a faceted crust buried about 16" deep.  

Avalanche Discussion

Overnight a modest storm arrived and as of 5 am, CBMR received just over 2 inches and Schofield Pass appears to have the most with 5 inches.  Light snowfall is expected to continue early this morning and slowly taper off into the afternoon.  Totals may reach up to 8 inches for areas in the Northwest Mountains.  The winds are a significant part of the avalanche forecast for today.  Yesterday afternoon, southwest winds ramped up to 40 mph with gusts hitting 70 at Scarp Ridge (Weather Station page).  Sometime this morning winds should shift to the northwest which will increase the volume of terrain that receives wind loading.

In the Northwest Mountains, the primary avalanche concern lies with the freshly drifted snow and the Wind Slab problem.  It is possible that a moving avalanche in the recently drifted snow could pry loose a larger avalanche a few feet deeper in places highlighted by the Persistent Slab distribution rose.  Considering this potential is prudent as an avalanche that breaks several feet deep will be large enough to bury, injure, or kill you.

In the Southeast Mountains, the primary concern depends on the overall depth of the snowpack.  For areas with greater than 5 feet of total depth, locations along the boundary with the Northwest Mountains, freshly forming Wind Slabs, and the associated potential for an avalanche to step down a foot or two are the main threat.  But in areas with an overall depth of fewer than 5 feet, particularly in the 3 to 4 range, there remains the potential for avalanches to break near the ground.  Last Wednesday two skiers had a close call on Park Cone when they triggered an avalanche on basal weak layers on a northwest-facing slope below treeline.  Park Cone resides outside the CBAC forecast area but similar snowpack depths and structures exist in snow-deprived portions of the Southeast Mountains forecast area.  If you are traveling through terrain with shallower snowpack depths in the Southeast Mountains, you should consider this low probability/high consequence possibility.  If you are in doubt about the chance of triggering an avalanche on deep weak layers in the Southeast Mountains simply choose lower-angled terrain around 30 degrees or less.

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