Boletín de aludes

Presidential Range

Mount Washington Avalanche Center
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Peligro de aludes

Thu
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

A mixture of early morning rains and afternoon snow will change the avalanche problems throughout the day. A volatile wet slab avalanche scenario will transition to a dry snow wind slab avalanche problem with a dramatic change in temperature this afternoon. Adjust your plans accordingly and prepare for icy conditions with crampons and the ability to self arrest in the event of a fall.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    After temperatures plummet below freezing in the early afternoon we can expect scattered snow showers with a possible accumulation of 1-2 inches. Strong west to northwest winds will prevail on the higher summits driving the new snow onto leeward aspects on the eastern spectrum of the compass. Drifted snow will collect at a rapid rate in the middle and upper elevations leaving behind slabs that could be up to 1 foot thick. Some drifted slabs could be sensitive to human triggering.

  • Wet Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    1–2

    This morning as rain continues falling on saturated and firm snow surfaces expect to find widening cracks and pooling of runoff in some locations. Slushy, loose wet avalanches are possible on the snow surface, while excess water percolates through to the subsurface of the snowpack. The added lubrication between snowpack layers or at the ground/snowpack interface, can allow larger areas of the snowpack to potentially creep or ultimately fail catastrophically. If today's weather scenario plays out we could receive nearly 1 inch of rain until it changes to snow. It could take several hours for the rain water to fully drain from the snowpack leaving this problem lingering well after the change from rain to snow occurs. 

Avalanche Discussion

An unfriendly mixture of weather is on tap for today with early morning rain changing to ice and afternoon snow. The warm and wet air mass above us moving northeast is being pushed by a colder and faster system with a steep pressure gradient. In this exchange we will see dramatic changes in temperature and increasing wind speeds near ridgelines. Projections predict that gusts around 140mph could be reached near the 6288 foot mark of Mount Washington summit.

Timing is critical today if you are adventuring in one of “North America's places to find the worst weather.” You will need protection from the rain early in the day and multiple forms of traction and self arrest while descending. 2PM will likely be the timeframe for transitioning from rain to snow in the middle and upper elevations. Expect increasing westerly winds and sticky precipitation in multiple forms.

As the mountain snowpack gains water weight it can add stress to the layers and the overall pack as whole can be affected. Pooling water, undermined structure and catastrophic failures in the snowpack can present themselves in different forms across the landscape. Pressurized water bulges can become a serious hazard if you are in the vicinity of them, creating holes and moving torrents of heavy saturated snow downhill. Cracks and openings in the snowpack indicate movement of large areas of the snowpack, and they are hard to predict. Today is a good day to observe changes in the snowpack without getting yourself into harm's way on steep avalanche prone terrain.  

Thanks to everyone who has taken 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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