Boletín de aludes

Boletín de aludes

Payette Avalanche Center
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Peligro de aludes

Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche hazard is Moderate today.   Potentially record-breaking high temperatures are forecasted through Sunday with little to no overnight refreezing of the snowpack.  Wet loose avalanche activity was widespread yesterday and will be again today.  Multiple weak layers and crusts exist in the upper two to three feet of the snowpack and are now saturated by the melting snow above.   The potential for larger wet loose and naturally occurring wet slab avalanches will increase through the day as temperatures warm.  Avoid traveling in steep terrain as the snowpack continues to weaken today and over the next few days.

 

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    1–1.5

    Yesterday felt like one of the warmest days of the winter and upper elevations did not cool below freezing for more than an hour yesterday morning. Today, temperatures are forecasted to be warm again and as of 6 am,  the temperature at 7600 ft is 33.  These temperatures are not allowing the snowpack to refreeze below the surface and are weakening the snowpack more each day.  Yesterday morning near Lick Creek Summit, we started seeing an increase in natural wet loose activity around 11 am.  As the day warmed, the frequency and size of these increased.  Even northerly,  mostly shaded terrain above 7500 ft had shed or was shedding snow off of the surface.  You can expect more of the same today.  Oftentimes, wet loose avalanches begin as small point releases and can easily grow in size as they travel and grab more wet snow in their path.  Pay attention to the terrain as temperatures warm and avoid steep slopes and terrain traps like gullies and avalanche paths.

  • Wet Slabs

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

    With a rapidly warming snowpack, meltwater begins to seep down through the snowpack.  As we transition away from a cold snowpack and the persistent weak layers that we have been talking about over the last few weeks get saturated by this meltwater, there is a growing potential for natural wet slab avalanches on the weak layers or the crusts that are now buried between 1 and 3 feet deep in the snowpack.  Wet slab avalanches are like big, rogue waves.  They are unpredictable and relatively rare until conditions line up.  All of the conditions are lining up with the weak layers in the snowpack and potentially record-breaking temperatures.  Temperatures over the next few days will be increasing each day adding to the problem.  Overnight temperatures are not predicted to start cooling off until early next week and the snowpack will take several days to refreeze once temps start to drop.  Wet slabs require a healthy dose of respect as they can be very destructive and unsurvivable if you were unlucky to be the trigger or below one when it started.  Avoiding steep terrain and giving the snowpack a chance to heal after this heatwave are your best choices right now.

    Yesterday we observed wet or saturated snow down at least 60 cms(24 inches) in the snowpack.  Both of the crust/weak layers were allowing water to pool above them creating the perfect lubrication for a wet slab above (see photo).

Avalanche Discussion

Today's Advisory is sponsored by Brundage Mountain Resort. Thank You For Supporting the Payette Avalanche Center!

For better or worse, Spring is here and the temperatures over the next few days will reflect it. Temperatures are expected to climb through the week to 5-15 degrees above normal. With full sun, we will undoubtedly experience an increase in wet avalanche activity. Wet loose avalanches are typically fairly predictable and manageable and involve mostly just the surface of the snowpack. As the day gets warmer and the snow becomes more saturated, the hazard of wet loose avalanches rises and can involve more of the snowpack   Wet slab avalanches are another type of wet snow avalanche and are different beasts than wet loose.  They are much more difficult to predict and can be much larger and more destructive than loose avalanches.  Cornice failure is another side effect of a rapid warm-up,  I don't travel under cornices during warm weather at all.

Our snowpack has several key ingredients that should make you wary of the possibility of wet slab avalanches over the next few days.

  1. Persistent weak layers buried within the upper 2-3 feet of the snowpack
  2. A variety of different crusts in the upper snowpack
  3. Abnormally warm temperatures that are flooding the snowpack with meltwater which is allowing the snowpack and the weak layers to become saturated and lubricating crusts.
  4. Failing cornices- there are some large cornices that will be failing with the heat and bombing slopes below with tons of weight.

As the temps soar this week, we need to be thinking of changing avalanche hazards and the possibility of abnormal avalanche conditions.