Lawinenlagebericht

Presidential Range

Mount Washington Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
Keine Stufe
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Wind transported snow has formed cohesive slabs on east-facing slopes. These wind-drifted slabs could appear smooth and sound hollow but react brittle when approached, resulting in a collapse that could create a large avalanche. Avoiding recently drifted snow and skiers traveling above, can help you steer clear from today's avalanche problem.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Blown snow has formed slabs on east facing slopes which could produce a large avalanche. Natural avalanches are unlikely, but a human triggered avalanche may occur in previously drifted slabs in sheltered areas. Wind drifted snow on slopes over 35 degrees in steepness may appear smooth and rounded with a hollow characteristic as you approach them. 

    In some locations dense spherical grains of snow have poured down from the slopes above and have gathered in depressions. Rimed snow particles and their not-so-distant relative graupel, were observed during Sunday's recent snow. This form of precipitation occurs during super-saturated and unsettled weather events and can in certain instances be a catalyst for slab avalanches.

Avalanche Discussion

Sunday’s half foot of snow and the previous few days of lingering upslope showers, have contributed to the current wind slab avalanche problem. Strong northwest winds overnight, which reached a peak gust of 99mph, have stripped the upper elevation snow and formed slabs below. These drifted snow layers could fail with the weight of a human traveling across them causing a large enough avalanche to bury a person. 

Observers in the field yesterday reported overcast skies with lingering upslope showers and blowing snow. Wind transported snow was collecting on eastern slopes and being scoured from western aspects of the snowfields above. Most stability tests that were done concluded that with moderate forces applied to them, slabs of condensed and drifted snow will fail in isolated locations. Much of the resulting failures were above or within a layer of snow grains that were either rimed particles or graupel. Extreme winds overnight may have pressed these slabs into the slope making some of them unreactive while in other locations it may have exacerbated the danger.

Firm and icy slopes still remain for much of the surface area in skiable terrain. Crampons and self arrest tools are highly recommended, and should be a necessary tool for travelers on our transitioning snowpack, for the rest of the season.

When creating an avalanche forecast for an entire range of mountains we cannot be in all places, nor across each slope and aspect. Inherently a bit of uncertainty exists within our messaging and that is why we rely upon your input and observations to bring more accuracy to this product. Thanks to everyone who has taken the time to submit observations of snow and avalanche conditions, both inside and outside our avalanche forecast area. Please keep them coming.

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

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