Bulletin d’avalanche

Northern New Mexico

Taos Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
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

You can trigger a wind or persistent slab avalanche in steep open wind exposed terrain. Wind drifted slabs have formed on top of a variety of different surfaces and may not be bonding well to the old existing surfaces. These cohesive slabs now rest on top of several faceted weak layers that will produce a larger more dangerous persistent slab avalanche. Careful snowpack evaluation, cautious route-finding, and conservative decision making are essential today. 

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Wind drifted snow continues to stress and cap several faceted persistent weak layers in the snowpack.  Buried near-surface facets beneath wind crusts from last week's wind events will be the easiest and most likely layer to trigger a persistent slab avalanche. Our shallow snowpack has several layers of weak facets sandwiched between decomposing slabs in the mid-pack and near the ground.  There is a good likelihood that a smaller avalanche failing in upper weak layers may step down into these deeper weak layers creating a large destructive avalanche that may not be survivable. 

    Pay attention to obvious signs of instability like collapsing and shooting cracks.   Avoid being on or connected to slopes greater than 30 degrees as you can trigger avalanches from long distances today. 

    New wind drifted snow now rests as a cohesive slab on top of several faceted weak layers.

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Variable winds throughout the storm have now shifted to the SW and are currently in the 20's gusting in the 30 mph range.  With lots of snow available for transport, wind drifted slabs will continue to grow near and above treeline. These slabs have formed on a variety of different surfaces from crusts to near-surface facets and may not be bonding well to the old existing surface.  You will be able to trigger wind slab avalanches on slopes where you find 8 or more inches of accumulated or wind drifted snow, especially in areas like the leeward side of ridgelines and in cross-loaded gullies or terrain. 

     Pay attention to wind drifted pillows and shooting cracks on the surface. Any smaller wind slab avalanche has a good likelihood of stepping down into deeper weak layers creating a larger more destructive avalanche

    Obvious wind drifted pillow near treeline that while approaching the slope we got to collapse and crack.

Avalanche Discussion

Storm totals from Monday night/Tuesday's storm were 4 to 8 inches with .4 to .6" of snow water equivalent (SWE). This was very much an elevational snowstorm with lesser amounts at lower elevations.  E/SE winds were moderate to strong in the early morning hours of Tuesday before calming down during the day yesterday.  Winds shifted to the SW overnight and picked up and are currently this morning in the 20's gusting in the 30 mph range.  With lots of snow available for transport, these winds will easily be moving snow around today.

This wasn't the biggest of storms, but it didn't take much to create sensitive touchy avalanche conditions yesterday.  In travels, we were getting several loud audible collapses and shooting cracks as well as triggered a small persistent slab avalanche on a test slope from well below the crown.  Wind drifted slabs up to a foot in depth were observed on open slopes near treeline creating cohesive slabs and adding stress to the persistent weak layers in the snowpack.  Slopes that we were traveling on before the storm without any results are now reactive where we are getting avalanches or collapses and shooting cracks. 

Below treeline, we received less snow and had less wind, but there may be open exposed slopes that have enough of a cohesive slab to be able to propagate resting on top of weak facets. The snowpack at these elevations is mainly cohesionless facets with the new snow on top that you can see in the video in the media gallery.  In steep terrain, you can produce small loose snow avalanches that entrains the entire snowpack.  This could sweep you off your feet and drag you into natural obstacles or terrain traps.  

Unfortunately, this wasn't a big enough storm to tip the scales that would've flushed all the facets in the snowpack with a widespread natural avalanche cycle.  Looking ahead with a more active weather pattern in the forecast, it's looking more and more like we're going to be incrementally loading slopes with smaller storms and wind events.  With not much time for persistent weak layers to adjust in between storms, smaller accumulations can quickly add up that in effect act like a bigger storm.

With skies clearing this afternoon and warm temperatures, we may see small loose snow sluffs in steep terrain that could have the ability to step down into deeper weak layers.

Skiing and riding conditions have greatly improved with this latest round of snow. The safest place to be today is on low angled wind-sheltered terrain. 

Régions couvertes