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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In sintesi

You could trigger a small avalanche in wind-drifted snow on steep south-facing, east-facing, and north-facing terrain above 3000 feet. Larger, more destructive avalanches are possible on east-facing and south-facing slopes above 3000 feet if you find a thin spot in the snowpack. Carefully planned route finding, terrain management, and snowpack assessment are critical for safe travel in avalanche terrain today. 

Problemi valanghivi

  • Wind Slabs

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

    What and where is it:Wind slabs from new snow and wind can be found primarily on easterly aspects and where the terrain has created protection from the wind. These slabs may be sensitive to the weight of a person. Features that may be harboring a more sensitive wind slab could be underneath ridgelines, cliffs, convex features, or in narrow gullies.

    How can you recognize it: Look for rounded, smooth pillowy areas of new snow. Snow blowing at ridgelines, cracking under your feet, or softer snow that is deeper than the top of your boot are warning signs of the avalanche problem. Deeper drifts represent a bigger avalanche problem. 

    How can you manage it:Identify wind-loaded areas and assess your exposure based on the consequences of a slide. Using a ski pole, probe, or your boot penetration will help you to assess the size. To limit your exposure to wind slab avalanches, avoid deeper snow drifts and travel strategically in avalanche terrain.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    What and where is it:Old, hard slabs are sitting on a buried persistent weak layer showing potential for instability above an ice crust bed surface. Forecasters have identified this structure as having the potential to slide on east and south aspects above 4000 feet, specifically in the Summit Snowfields, Summer Lion Head Trail, and gully entrances on the south face of Tuckerman Ravine. These slabs are up to 1 meter deep and could produce a dangerously large avalanche with serious consequences. Note that this avalanche problem exists just to the north of where the Lion Head Trail leads to Split Rock on the summit cone.

    How can you recognize it: Identifying this avalanche problem is difficult without digging a deep pit, as there will be no visible clues. "Whumping" sounds as a warning are unlikely, and the slopes will likely appear unreactive.

    How can you manage it:Understanding where there are likely trigger points for this avalanche can be challenging or impossible. Careful and strategic route finding, terrain management, and minimizing exposure time are critical if you choose to travel in avalanche terrain.

Avalanche Discussion

Some uncertainty exists around the new snow amounts and warming temperatures that are expected tonight. If heavy snow begins earlier than forecast and accumulations are over a few inches, avalanche conditions could become more dangerous. 

Multiple observations from the last two days (Obs 1, Obs 2, Obs 3, Obs 4) showed recently formed wind slabs to be reactive to a person’s weight. As new snow and wind-loading have continued overnight, expect to find similar reactive conditions of small wind slabs. Actively take steps to identify areas of concern and use travel techniques that minimize your hazard exposure. 

The MWAC team has been identifying locations of a persistent weak layer on east-facing and south-facing terrain that has developed enough to be a concerning avalanche problem moving into the foreseeable future. Triggering this layer is unlikely, however, finding a thin spot in the slab, where your energy can more effectively impact the buried weak layer, could trigger a dangerous, large, hard slab avalanche. Without digging down into the snowpack, it won’t be possible to assess the reactivity and potential size of this avalanche problem. This is a risk that should be actively debated within your group before entering avalanche terrain. If you do decide to travel in avalanche terrain, take steps to minimize your exposure with strategic travel techniques and terrain management.

Regioni coperte