Lawinenlagebericht

Presidential Range

Mount Washington Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
Keine Stufe
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Kernpunkte

You could trigger an avalanche in wind drifted snow on steep easterly slopes above 3,000 feet of elevation. Carefully evaluate the snowpack and be mindful of deeper drifts to help mitigate your risk to this hazard. Above treeline, remain on hiking trails to avoid triggering an unlikely but consequential large avalanche.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    What and where is it: Today's northwest winds are transporting 3.5 inches of new snow, forming wind slabs on easterly aspects above 3,000 feet in elevation.

    How can you recognize it:  Try to look for rounded, smooth pillowy areas of new snow, though low visibility may limit observations from a distance. Red flags include cracking under your feet, or softer snow that is deeper than the top of your boot are all warning signs of the avalanche problem. Deeper drifts represent a bigger avalanche problem. Features that may be harboring a more sensitive wind slab could be underneath ridgelines, cliffs, convex features, or in narrow gullies.

    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 avalanche hazards, avoid the thicker wind slabs. Pay attention to slope angle as you travel, your chance of triggering a slide in a new wind slab increases as the slope angle increases above 30 degrees. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–2.5

    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 southeast aspects above treeline on Mt. Washington, specifically in the South and East Snowfields. These slabs are up to 100cm 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: The identified area of concern for this problem is well defined. Navigate around the Southeast and East Snowfields to avoid triggering a large avalanche. For those hiking to the summit via the Lionhead Trail, remain on the hiking trail to avoid this avalanche problem. 

Avalanche Discussion

While investigating a report of an avalanche on the Southeast Snowfields yesterday, forecasters identified a layer of faceting grains above a buried ice crust, which showed potential for instability. Triggering this layer is unlikely and easily avoidable; however, finding a thin spot in the slab could trigger a dangerous, large hard slab avalanche. Currently, this does not appear to be a widespread avalanche problem, but there is a possibility that reactivity in a similar structure could be found elsewhere.

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