Bulletin d’avalanche

Presidential Range

Mount Washington Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
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

Persistent warm temperatures and rain today will allow for the possibility of human-triggered avalanches on steep snow slopes on all aspects at middle and upper elevations. Avoiding large snowfields in steep terrain will reduce your exposure to an unpredictable wet avalanche.

Problèmes avalancheux

  • Wet Slabs

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

    The potential for wet slabs will increase during the day as above freezing temperatures continue and rain arrives later in the afternoon. The chance for triggering a small slide exists on all aspects - anywhere you find soft, penetrable snow on a steep slope. The largest slabs will be the most worrisome, capable of producing a D1.5 to D2 avalanche and can be found in some areas on northeast, east and southeast aspects at ravine level elevations. 

    Signs of instability for this problem include roller balls and pinwheels on steep slopes, deep boot or ski penetration into a soft or sloppy snowpack, and steady rainfall.

Avalanche Discussion

Even with limited snowpack distribution and the current disconnected nature of snow slopes, wet avalanches remain a concern moving into day 3 of significant warming and melting. Yesterday, signs of decreasing stability were observed including roller balls, pinwheels, wet sluffs, whumphing, and falling ice. These signs reflect the scary and unpredictable nature of a rapidly warming winter mountain environment. 

It's important to address the uncertainty associated with forecasting wet snow avalanches. Two things are needed: a weakness in the snowpack and water from melting. Today, there is certainly some free water moving through the snowpack as temperatures in the alpine did not drop below freezing last night. Recent observations show a lack of spatial uniformity both in distribution and stability. Obs1 Obs2 Obs3. Generally speaking, recent field observations suggest good stability in the recently formed slabs going into this warming event. Warming and rain today will continue to work to decrease stability. If and when slopes become unglued it will be hard to predict. Unfortunately, the only way to manage uncertainty is avoidance. Stepping back from very steep, consequential terrain is prudent wherever water is moving down into the snowpack.

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