Boletín de aludes

Gunnison

Crested Butte Avalanche Center
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Peligro de aludes

Wed
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The 1 to 2" of new snow overnight will do little to change the current avalanche conditions. The expectantly dry start for 2021 has left our snowpack generally stable. Human triggering a slab avalanche has become unlikely, due to the stubborn and isolated characteristics of the current avalanche problem. Stay alert for those isolated areas. These isolated areas would primarly be found on the lee sides of cross-loaded terrain featuers, or below ridgelines, where previous winds have left hard slabs over weak snow. A skier found just the right location yesterday and triggered a small slab into a higher consequence terrain feature. 

Problemas de aludes

  • Persistent Slabs

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

    The odds of triggering a persistent slab continue to decrease under our current snow drought.  On steep terrain features with previous windloading, you may be able to trigger persistent slabs up to several feet thick that fail on weak snow near the ground. Even below treeline, shallow pockets of hard slab exist in a few leeward terrain features.   Persistent slabs often surprise even the most experienced travelers because they give infrequent or irregular feedback.  To avoid this problem,  choose routes that stay off of steep terrain holding dense slabs over sugary weak layers.   You can read the snow texture and avoid terrain where the snowpack looks or feels deeper, denser, and more windloaded to help you avoid the problem.  The most concerning slopes are on northeast, east, and high southeast facing terrain.  You may be able to find isolated exceptions to the distribution rose on cross-loaded terrain features on other shady aspects.  Riding on steep terrain where the snowpack is softer and faceted throughout is the safest option.

    1.18 Small skier triggered hard slab on a cross loaded terrain feature. This avalanche ran into a higher consequence terrain trap formed by the Slate River below.

Avalanche Discussion

I'm doing my snow dance as I type this morning and hoping for the best. We are not in a favorable location for the current storm, and exceeding the snow forecast is unlikely. If we were to get lucky, the Southeast Mountains would see the best accumulating snow due to the prevailing wind direction. If you found near 5" of new snow today, then you would be in an area that is exceeding the forecast. That new snow would add volume to loose snow avalanches in steep terrain, and potentially start creating a shallow storm slab avalanche problem where the old snow below is exceptionally weak.

Since the extreme wind-event mid-last week, all the human-triggered slab avalanche results have come from below treeline elevations. Previous to that wind event those lower elevations had almost completely faceted out and were lacking a slab. After that wind event, there are now a few location holding a hard slab over that weak snow. Below treeline elevations were added into the avalanche problem rose this morning for that reason. It's hard to say what elevation would be most likely to trigger a persistent slab avalanche at the moment, instead, the problem fits unlikely at all elevations. The potential avalanche size would simply grow from, generally small at lower elevations, to potentially large at mid and upper elevations. 

Yesterday's human triggered observation is a good read. Big thanks to the individual for sharing, and for taking the time to explain how they became a bit complacent about current conditions. Human factor traps happen to the best of us. Obvious red flags to instability no longer exist, so you will not get those early warning signs. You must continue to remind yourself that avalanches are unlikely to trigger at low danger, not impossible... The previously wind-loaded terrain, that would be most suspect for human triggering, will now be harder to identify with a fresh dusting of new snow. 

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