Bollettino valanghe

Northern New Mexico

Taos Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Another round of low-density snow from a quick-moving system has pushed snow totals to 4 - 8 inches over the last couple of days.  Moderate winds overnight at ridgetops have created soft wind slabs on the leeward sides of ridglines and in cross-loaded terrain above treeline.  Avoid obvious wind-drifted pillows and pay attention to clues of stiffening snow, like shooting cracks on the surface. With the sun popping out today, steep wind-sheltered slopes are where you could experience long-running loose dry snow sluffs that could occur naturally in steep terrain that is facing the sun. Evaluate snow and terrain carefully, identifying features of concern.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    4 to 8 inches of low-density new snow has fallen over the last couple of days combined with moderate winds overnight should drift snow into soft wind slabs at upper elevations. Wind directions have been shifting but expect to find wind drifted slabs just below the leeward sides of ridgelines and in cross-loaded terrain. These wind slabs have formed on top of firm smooth crusts or weaker faceted snow that will make for a nice bed surface.  Pay attention to changes in the surface, from obvious wind-drifted pillows, to textured snow like sastrugi and an overall stiffening of the snow.   Shooting cracks in the surface off of your tips are another indication you've found a wind slab.  These slabs could be upwards of a foot thick and able to move quickly down the slope on the firm bed surface beneath.  

    Winds peaked last night around 8 pm at the tail end of last night's storm, dropping back into the teens with gusts in the 20 mph range. 

Avalanche Discussion

Snow started around 5 PM last night as another quick moving system deposited 2 to 4 inches of low-density snow bringing snow totals over the last couple of days to 4 to 8".  Winds picked up overnight at ridgetops and should easily have transported snow above treeline into thicker wind slabs on the leeward sides of ridgelines and in cross-loaded terrain. The avalanche concerns for today are with the new snow over the last couple of days and the old snow interface.  Steep wind-sheltered terrain has the potential for long-running dry loose snow sluffs that typically start around rock bands as the sun warms the darker surface. These types of avalanches typically aren't that big of concern but could be if you're in high consequence terrain above cliffs   

The three weeks of high pressure to begin January has done a lot to transform the old snow surface before these last couple of storms.  These last couple of storms have fallen on a variety of different surfaces ranging from melt-freeze/sun crusts on solar aspects and lower elevation terrain, to old decomposing wind slabs in the alpine and weak faceted snow on wind-sheltered northerly aspects. All of these combinations of the old snow surface are making for a good sliding surface for any potential new snow avalanche.       

So what happened with the persistent slab problem of facets and depth hoar on or near the ground on upper elevation terrain? In recent snowpits these layers continue to remain present but are taking hard force to fail and propagate or are not failing at all.  These persistent weak layers will continue to remain dormant for now until we wait for a significant load, where they may become more reactive.     

 

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