Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Sun
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

Your primary avalanche concerns are for small loose wet avalanches, and lingering wind slabs at upper elevations. While many areas were cooked yesterday, you can still find some locations to trigger a loose wet avalanche today. Conditions for this avalanche problem will require a few inches of wet snow on the surface and maybe more common on the northern half of the compass than the southern half. Any lingering wind slab concerns primarily exist above 12,000ft in the Ruby Range or the northern Elk Mountains. Riding conditions look the best during the first half of the day before cloud cover and winds increase this afternoon. 

Problemas de aludes

  • Loose Wet

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

    Small loose wet avalanches will become possible to human trigger when you find a few inches of wet snow on the snow surface. This avalanche problem has already been cooked away in many areas. The most likely areas to now find this avalanche problem would be on the northern half of the compass at near and below treeline elevations, and on the southern half of the compass at elevations near or above 12,000ft. Increasing winds and clouds this afternoon will help decrease this avalanche problem, but the forecasted warm temperatures may keep the avalanche problem persisting through the day on wind-sheltered terrain. 

    Loose wet avalanche activity near East Beckwith. 4/15

  • Wind Slabs

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

    This past week has been dominated by moderate to strong winds from the west to southwest, with a few small snowstorms adding some fuel for wind slab formation. Elevations above 12,000ft in the Ruby Range and the northern Elk Mountains would be the most likely areas to find a lingering wind slab today. These slabs have become stubborn to trigger. A wind slab is classically represented by a rounded or lens-shaped snow deposit, where additional snow has accumulated on the lee side of the terrain feature. Shooting cracks, active snow transport, and fresh cornice formation all point to Wind Slab formation.

    Blowing snow on Scarps Ridge. 4/15.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    1.5–2

    Slab avalanches breaking into old weak layers several feet deep have become unlikely.  Higher elevation, northerly facing terrain still holds a dry, winterlike snowpack; thus we can't completely eliminate the potential for a rare but large slab avalanche on these aspects.  The most suspect terrain is where snow coverage is shallower,  especially on convex, unsupported slopes or near rock bands. You are most likely to trigger a slide from a shallower spot on the slope.  If you are skiing or riding in that type of terrain, reduce your group's exposure during uphill travel and choose appropriate safe zones from a large avalanche while descending.  Let your friend wrestle their stuck snowmobile off of suspect slopes by themselves.  A recent very large avalanche near Snowmass (observed 4/14) keeps this unlikely problem lingering in the minds of forecasters.

    Example of our most recent persistent slab avalanche that likely failed around March 30th.  This large avalanche highlights the type of terrain that remains most worrisome:  northerly, rocky, and unsupported.  

Avalanche Discussion

Yesterday, high temperatures at 11,000ft reached up around 40 degrees. The high sun angle this time of year further helped wet the snow surfaces on some northerly-facing slopes. Today's loose wet avalanche problem rose is a bit atypical as the majority of southerly facing slopes have already had any potential loose wet avalanche concerns baked away, while northerly facing slopes have more snow available to transition from dry to wet. High temperatures are forecasted to increase a few degrees today before cloud cover and winds increase this afternoon.

The wind slab avalanche problem was trimmed to just above treeline elevations in the NW Mountains. Those areas have held onto the most consistent blowing snow. While wind slabs at lower elevations were baked in by yesterday's warm temperatures. The SE Mountains have seen little snow accumulate this week and any lingering wind slabs are further isolated in that area. 

There is a small chance for some new snow to accumulate overnight. If we do manage to squeak out a couple of inches of snow, then we'll be again talking about that snow transitioning from dry to wet tomorrow and continuing a loose wet avalanche problem. Otherwise, if we don't see any snow accumulate, high temperatures are expected to be a few degrees colder tomorrow and wet avalanche concerns will be further diminished. The elevated winds will probably keep wind slabs on the problem list for Sunday. 

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