Bulletin d’avalanche

Presidential Range

Mount Washington Avalanche Center
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Danger d’avalanche

Wed
Alpin
1 · Faible
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

It may be possible to trigger a small avalanche of wind drifted snow at middle and upper elevations in areas that have been protected from the wind. Use caution in steep terrain, where the consequences of a small avalanche could be serious.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    In wind-sheltered areas, it is possible to find small wind slabs formed from recent wind-transported snow. The chance of encountering these wind slabs exists primarily on east and south aspects at middle and upper elevations underneath large cliffs, rock features, and in snow gullies. When looking for this problem, watch out for new, softer snow cracking or sliding easily on top of an old, icy snow surface. If the penetration of your boot into the snow becomes deeper and deeper, it may be worth re-evaluating the travel plan to avoid these deeper pockets.

Avalanche Discussion

Even with a LOW rating, triggering an avalanche on steep, wind-sheltered terrain features is not out of the question today. The few areas that look enjoyable to ski or ride are also some of the areas of greatest concern today, since they also happen to be the most developed snow slopes. 

Recent accumulations of upslope snow showers have allowed small wind slabs to build in lee and protected areas on top of a slick, icy rain crust. Field assessments yesterday revealed poor bonding of new snow to a widespread rain crust that is variable in thickness and hardness. New snow depth on top of the crust was observed to be 1 to 6 inches deep depending on shelter from the wind. In steeper, sheltered terrain, this snow could be deeper and could have formed a small slab. A few inches of incoming snow tomorrow may further develop these slabs and raise the avalanche hazard.

Underneath the rain crust, previous storm snow has been faceting into larger, weaker snow grains with persistent cold temperatures and a shallow snowpack. It is not an avalanche concern now, but it could be in the future. The forecast team will be keeping an eye on this weak layer and the ability for the rain crust and future snow to bridge the weight of a potential trigger. 

Long Sliding Falls: Traveling in steep avalanche terrain today will require full mountaineering equipment including stiff boots, crampons, and an ice ax. Long sliding falls are dangerous, injuring or killing more people than avalanches in our forecast area.

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. 

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

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