Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You could trigger a large avalanche in wind drifted smooth snow in east and south facing terrain. Look out for deeper snow and areas of bright white, pillow shaped snow to indicate the avalanche problem. Travel on wind textured snow surfaces to avoid these areas of potentially unstable snow.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    You can find this problem in sheltered terrain features as rounded, pillowy pockets on east and south facing slopes between 3000-5000 ft of elevation. Steep rollovers, convexities, and sheltered terrain will be where the greatest potential instabilities remain. Because of the spatial variability of this problem, identifying it will be easy as the smooth snow will be in contrast to the textured snow around it.

    Areas of unstable snow have been found in softer, and deeper drifts. If you find yourself in a deeper pocket with snow above your boot tops, this is a time to consider reevaluating. Test the sensitivity with hand shears by digging down to the interface of the old snow and consider potential consequences as many of these sheltered pillowy snow drifts are harbored above exposed rocks and trees.

    Wind loaded and rounded, pillowy snow in Chute is an example of terrain features to carefully evaluate today. Additionally as they will be easy to identify, they will be easy to avoid.

Avalanche Discussion

Observations from Tuckerman Ravine yesterday found various hand hardness changes between the interfaces of wind slabs that have built from the 18.4 inches of new snow over the past week. Observers were continuing to find stubborn results and found that yesterday’s solar gain was working to promote bonding and increase stability within these wind slabs. Today, additional warming could create initial instabilities as the warming melts layers and lubricates them, but overtime this warming is more likely to promote additional healing and bonding of potential lingering instabilities. 

Most of the new snow over the last few days has been localized to the upper elevations, where middle and lower elevations did not record any precipitation. Because of this we have removed the wind slab problem from low elevations since it has not had the additional snow loading that terrain. Something to consider today in Crawford is more warming than forecast. Previous observations from Crawford Notch  discuss snow on an icy surface. Warming today could wet and lubricate this snow that could more easily slide on a slick bed surface. This seems unlikely based on forecast temperatures and cloud coverage, but if skies clear and warm the surface rapidly this is something to consider if you are in Crawford today. Lookout for rollerballs and mushy snow as indicators of potentially unstable snow.

A final take away for today is that ski tracks do not guarantee stability. These wind slabs have consistently produced stubborn results, but there are areas of increased sensitivity. The spatial variability of this problem makes it challenging to truly know the sensitivity across a slope. Do not get lulled into complacency knowing that someone skied this same slope previously. Evaluate terrain and consider the features where snow is more likely to harbor remaining instabilities.

Regioni coperte