Bulletin d’avalanche

Northern New Mexico

Taos Avalanche Center
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Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Triggering a persistent slab avalanche remains possible on West through Southeast-facing terrain at all elevations. 2 to 4ft thick slabs and deeply buried weak faceted snow means we are dealing with the potential to trigger large to very large avalanches. The uncertainty and high consequences of getting it wrong have us seeking wind sheltered terrain less than 35 degrees.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    2 to 4 ft foot slabs formed from the end of January storms rest on top of several faceted weak layers and depth hoar near the ground.  Although it's been a week since the last significant loading event, strong west winds have been creating stiffer slabs on the surface and are slowly loading slopes that hang delicately in the balance. A couple of natural avalanches from 4 or 5 days ago near and above treeline speak to how fragile the deeper faceted weak layers continue to be.  These were large to very large avalanches and would've been unsurvivable. Below treeline, these persistent slab avalanches may be smaller but could have serious consequences if they take you over a cliff or bury you in a terrain trap.  

    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.  

    Large natural avalanche on a cross-loaded west gully near treeline. The avalanche failed on facets 2 to 5 feet down in the snowpack.

Avalanche Discussion

We are moving farther and farther away from our last loading event and/or significant change in our snowpack. Weak layers have had a little bit of time to adjust and we're not experiencing the collapsing or shooting cracks from last week. However, the snowpack structure is still concerning and I just don't trust it yet. 2 to 4ft slabs rest over several layers of weak faceted snow creating the concern for triggering D2-D3 size avalanches. These would be very difficult to survive if you found yourself caught in one. 

Above treeline, we have hard slabs formed from previous strong wind events littered across our terrain. You would have to dig or probe around to identify their presence as some slopes, specifically, ones that avalanched previously may not still have this slab. Dealing with hard slabs is difficult, they make it more difficult to affect weak layers buried beneath them but at the same time, they communicate propagation extremely well. Hard slabs also behave in unpredictable ways, for example, it may not be the first few people on the slope that trigger an avalanche, they have a habit of fracturing well above once you've already committed to the slope. You're most likely to impact buried weak layers around areas where the slab or snowpack is thinnest, but this can be a very difficult thing to assess on the surface. Rock outcroppings or the margins of the terrain feature are likely areas to find these characteristics. 

In more wind-sheltered terrain near and below treeline our strong diurnal temperature swings have been chipping away at the strength of our slabs. In these areas, lacking the hard slab, if you take away the slab formed from our last storm event we're just left with a faceted snowpack. So, losing strength in our slabs here is a step in the right direction, however, we don't feel like we're quite there yet. The 2 to 3 feet of snow that fell and consolidated is quite a bit for the faceting process to have to chew through. As you're traveling through this type of terrain pay attention to the slab properties, especially in open terrain that's more exposed to the wind. 

It'll be another warm day out there today so keep loose wet avalanches on you're radar. Recently, strong winds have kept this concern at bay for the most part but look too steep southerly aspects, especially in and around rock outcroppings to be the most likely areas to see small point release loose wet avalanches today. 

 

 

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