Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Triggering a large avalanche of wind drifted snow 1- 3 feet thick is possible today, especially in east-facing ravines such as Tuckerman Ravine and Gulf of Slides. An avalanche will be more likely where the wind has formed drifts from the recent snow. Identify areas of concern by looking for a smooth, pillow-like snow surface. You can reduce your risk of triggering an avalanche by avoiding steep slopes loaded with wind drifted snow.

Problemi valanghivi

  • Wind Slabs

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

    Large, human-triggered wind slab avalanches are possible today in wind-sheltered areas on steep terrain features that face north, east, and south. The most likely trigger points are in the steepest sections of avalanche paths where smooth, softer snow is present. 

    Multiple crust layers and density changes in the top 1 - 3 feet of the snowpack have the potential to act as a slick bed surface for this avalanche problem. Dig down to assess the stability of these interfaces while understanding that variability exists across the terrain. Practice safe travel techniques and good terrain management by traveling one-at-a-time in avalanche terrain and reduce overhead hazard with careful, strategic route planning.

    Small, thin wind slabs in wind-sheltered terrain may be reactive to the weight of a person today. To assess this problem, assess how well new snow has bonded to the old snow surface. Watch for shooting cracks and poor bonding of new snow to the snow surface.

Avalanche Discussion

In addition to the thicker slabs that are talked about in the wind slab description, small new wind slabs may continue to develop today and tonight with snow showers and wind. Yesterday, light density new snow created thin, reactive slabs in very sheltered terrain, but struggled to form slabs in exposed gullies and higher elevations. Any new wind slab development today should be easy to assess and small. The greater concern today are thicker wind slabs that are less reactive, but carry big consequences. Look for multiple sub-surface crust layers and some subtle mid-slab density changes if you are interested in investigating this problem further. 

The development of a persistent weak layer adjacent to a melt/freeze crust layer that likely formed on January 13 contains weak faceted grains trapped between two harder crust layers. This poor snowpack structure, which has been observed in several areas, has not been producing avalanches. We will be watching for continued degradation of the crust and facet development which could eventually turn this layer of concern into an avalanche problem. 

The Lion Head Summer Trail is CLOSED due to increased avalanche hazard. The Lion Head Winter Route is OPEN and the most direct route to the Mount Washington Summit from Pinkham Notch. 

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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