Boletín de aludes

Northern New Mexico

Taos Avalanche Center
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Peligro de aludes

Thu
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
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

Triggering a persistent slab avalanche remains possible on West through Southeast-facing terrain near and above treeline. Faceted persistent weak layers continue to linger deeper down in the snowpack and have been slow to heal and strengthen. Below treeline the avalanche danger is LOW but continues to remain weak with isolated steep open slopes remaining suspect.  Before committing to a slope, take the time to dig down to assesses if this strong over weak snowpack structure exists. Avoiding being on or connected to slopes steeper than 35 degrees is a great way to stay safe today. Any avalanche triggered today has the potential to be large and very dangerous.

Problemas de aludes

  • Persistent Slabs

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

    Moderate to strong westerly winds over the last week have created stiffening harder slabs on the surface near and above treeline on the leeward side of ridgelines and cross-loaded slopes.  These smooth in appearance slabs are capping the 2 to 4 feet thick storm snow from the end of January storms. These slabs rest on top of faceted weak layers and depth hoar near the ground that has been slow to heal and strengthen.  Natural avalanches over the last week have failed on weak layers near the ground taking with it the entire season's snowpack and were large to very large avalanches that would've been unsurvivable. 

    We are starting to see a lot of variability throughout the snowpack with some slopes still having a shallow snowpack and faceted weak layers struggling to heal and strengthen.  Wind-loaded slopes on the leeward side of ridgelines and in cross-loaded terrain especially near and above treeline have deeper snowpacks (2 m) with harder to trigger weak layers that may just take you finding a likely trigger point where the slab is thinner on the margins of the slab or near rock outcrops.   

    Obvious signs of instability like shooting cracks and loud audible collapses may not be present in travels. Taking the time to dig down deeper into the snowpack is the only way to assess whether this strong over weak snowpack structure exists. To mitigate the hazard, avoid being on or connected to slopes steeper than 35 degrees as you may be able to trigger an avalanche from below and these avalanches may run long distances.  

    A shallower snowpack on a NNE aspect near treeline. Weak faceted snow continues to linger below a hard slab that formed from previous wind events.

Avalanche Discussion

As we move further away from the last significant loading event, avalanche activity has quieted down over the last several days. Triggering an avalanche has become more difficult but not impossible and may just mean hitting a "sweet spot" where the slab is thinner.  As we've seen with natural avalanches over the last week, these slides can be large to very large failing on faceted weak layers on or near the ground. These would be unmanageable avalanches if you triggered one.  It's this low likelihood but high consequence scenario that should give you pause before committing to a slope. Obvious signs of instability like cracking and collapsing most likely will not be present, and it may not be the first or second person on the slope to get it to fail. It's this false sense of security that may lure you into steeper more committing terrain. 

We're fortunate to be working with two high school students this season on a snow science project, and Ben does a great job of explaining an extended column test that fails on a deeper faceted weak layer from our tour yesterday.

Westerly winds have been moderate to strong over the last five days and although have not been transporting snow, they've been creating smooth, shiny stiffening hard slabs on the surface or helping strip and erode snow on others.  You may encounter a shallow wind drifted slab on the leeward side of ridgelines or in cross-loaded terrain near and above treeline.  A shallower slab avalanche has the potential to step down into deeper weak layers creating a larger more destructive avalanche.

Below treeline, we've dropped the avalanche danger to Low, but the snowpack at these elevations continues to remain weak but on many slopes lacks a cohesive slab needed to communicate propagation across a slope. Steep, wind-exposed slopes will be the most suspect at these elevations and a small avalanche could have serious consequences if it drags you through trees or buries you in a terrain trap.    

This has been the deadliest week for avalanches in the US in over a century (NYT Article).  As a community, we've done a great job of dialing back our terrain as we deal with a scary snowpack structure that has plagued much of the West this season.  Continue to remain diligent and patient as we start to look towards another active weather pattern starting Friday.  With every loading event this season we've seen an uptick in avalanche activity.  Expect that trend to continue over the weekend as snow totals add up.   

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