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 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Drifted slabs of wind blown snow are scattered across the eastern side of the range and may react unstable when disturbed. Hollow, untextured, with a rounded appearance, these isolated slabs could release carrying you in a small avalanche. Staying on wind hardened surfaces and avoiding soft slabs on steep slopes will give you a better margin of error.

Problemi valanghivi

  • Wind Slabs

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

    Slabs of wind deposited snow still linger on eastern aspects in the mid and upper elevations. Overnight frigid temperatures have preserved these tender slabs from adhering well to the bed-surface below. Settlement and stabilization is slowed by colder temperatures, which keeps our avalanche danger at Moderate for today's forecast period. These slabs could be brittle and have the ability to crack easily underfoot. The isolated nature of these slabs means that identifying and avoiding them is the name of the game. Slabs of wind driven snow will appear textureless, rounded, and contrast in appearance to the older snow surrounding.

Avalanche Discussion

The arctic air temperatures this morning has us thinking about the faceting process and how it relates to our current wind slab avalanche problem. When we get cold clear nights the surface and subsurface layers of the snowpack are modified by the transfer of energy and vapor through the snowpack. During this physical process the grains of snow become angular and decrease the surface area between them. Well bonded grains can become brittle and lose their elasticity. Faceting between snowpack layers and near the surface can compromise the integrity of the snowpack, as faceted snow now becomes the new weak interface.

Sometimes imperceptible to the untrained eye, thin layers of weak sugary snow can develop, become buried and increase the reactivity of the above slab. If you dig deep to the bottom of the snowpack you can find evidence of this faceting process by the handfuls of loose sugary grains that comprise the base of our shallow snowpack

The Lion Head Summer Trail is now closed for the season due to avalanche risk. The Lion Head Winter Route is open.

Please help us and your fellow skiers, riders, and climbers by submitting any pertinent or interesting observations to our website.  

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