Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

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

In sintesi

Lookout for small pockets of smooth, drifted snow in steep, wind-sheltered east and south-facing terrain. Traveling on firm, textured snow surfaces will limit your exposure as will choosing lower-angle terrain or terrain with fewer consequences.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1

    What and where is it:

    Wind slabs formed from the January 19th storm may still be found above 3000 feet in elevation on sheltered, steep slopes on east and south-facing terrain. These small slabs may still remain sensitive to human triggers and you are most likely to find them in areas that are sheltered from wind allowing the snow to accumulate and remain more reactive. Areas to look for these will be in steep terrain that is below cliffs, ridgelines, and in convex rollovers.

    How can you recognize it: 

    Pockets of drifted snow that look planar and smooth compared to textured snow around will be your visual indicators. As these wind slabs are now 4 days old, they are likely to have some wind effect and may be less obvious than when they were newly formed. If you find softer snow underfoot or hear or feel drum-like sounds under your feet that indicate hollow snow on steep terrain you are in a wind slab. 

    How can you manage it:

    Visually assessing terrain will be your best initial tool to identify areas that may harbour a wind slab. As you are moving around in the snow, traveling on firmer, supportable, and textured snow surfaces will limit your chances of triggering an avalanche. Pay attention to what is under your feet, if you find hollow snow or find deeper and softer snow it may be good to pause to assess. 

    Assess the size of the wind slab from your foot penetration or a ski pole and dig into the snow to assess the structure. You may find the slab well bonded to the slab beneath, or you could find a strong-over-weak structure which would be the more concerning of the two. Informal tests like hand shears or formal tests like extended column tests can help you to assess bonding and propagation potential.

    While this point data is useful, it does not guarantee stability of snow elsewhere. It is always simplest to assess the consequence of if an avalanche were to happen, what does the path travel through. You increase your exposure from even a small slide if the path has exposed rocks, trees, cliff bands, or terrain traps below.

    Summer Lion Head

    An area that is sheltered and could be harboring a wind slab with lingering sensitivity

    Photo: Charlotte MacDonald

Avalanche Discussion

Forecaster observations from Tuckerman Ravine yesterday found generally stable conditions with previous evidence of small D1 avalanches in Chute, Center Headwall, and Dodge’s Drop from earlier this week. Northeast aspects were found to be firm, supportable, and unreactive when assessed. South-facing terrain had softer snow and strong-over-weak structure in the surface slab. This slab was small, less than two inches, and stubborn, but this is the type of snow to assess when you are moving through terrain today. 

The persistently cold temperatures may still harbor lingering instabilities in some of these older wind slabs, so while unlikely to be large this is something that you should not take off of your radar just yet.

OBSERVATIONS: Please consider submitting an observation of what you are seeing in your travels. Submitting an observation hones your skills, informs other users, and improves our forecasts.

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