Bulletin d’avalanche

Presidential Range

Mount Washington Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanches large enough to bury a person are possible. These avalanches, which can be triggered by the weight of a single person, are most likely to occur on steep east and south-facing slopes where snow drifts appear smooth and rounded. Look for signs of recent avalanches, areas of softer snow, and shooting cracks under your feet as signs that the snow is unstable.

Later in the day and tonight, watch for new snow and wind forming thin wind drifts that could also cause a small avalanche.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    On east-facing and south-facing aspects at middle and upper elevations, expect to find wind slabs that are between 1 and 3 feet thick. Though these slabs are generally in isolated, wind-sheltered areas, they may also be in areas that are the most tempting to ski. These slabs have proven to be sensitive to the weight of a single person and have the ability to propagate across a large slope. Check out this observation from a human-triggered avalanche yesterday in Tuckerman Ravine. The most sensitive wind slabs are likely to be smooth and rounded in appearance when compared to areas of more stable snow which will appear textured, firm, and wind sculpted. Wind scoured snow surfaces with little or no soft snow will be the terrain choice to avoid triggering an avalanche. 

    Later in the day and tonight, the potential for 2 - 4 inches of new snow combined with wind could create thin wind slabs that are sensitive to the weight of a person. Blowing snow, increased snowfall and accumulation, and poor visibility are signs that these new wind slabs have started forming.

Avalanche Discussion

Today’s wind slabs lie above a variable surface including a hard melt-freeze crust, pooled graupel, and also existing moderately reactive slabs. A weak snow structure remains which supports propagation potential in more connected terrain. The potential exists for an avalanche to break to the side or above a person, creating a larger than expected avalanche. Finding an invisible thin spot in the snowpack may be all it takes for a single skier to trigger a destructive avalanche. 

Later in the day, new wind slab formation may make it difficult to identify the larger, more destructive slabs that will be covered by new snow. If you lose the ability to accurately and safely assess snowpack, it might be time to adjust your intended travel plan.

Safely traveling in avalanche terrain today will take careful identification of large wind slabs and thoughtful travel techniques that minimize your groups exposure to avalanche hazard. Having the willingness to turn around or adjust your travel plan if you find signs of instability or get an intuitive bad feeling is important today.

Good visibility yesterday allowed for assessment of the most recent natural avalanche cycle on the 23rd and 24th of February. Evidence of large natural avalanches were observed in a significant portion of ski and climbing terrain in Mount Washington’s eastern ravines. Be sure to check out our observations page for public and professional accounts of these avalanche events. 

 

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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