Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Triggering a slab of wind drifted snow up to 1 foot thick is possible today. Stiff drifts of consolidated snow are the problem and should steer you towards sheltered areas with softer snow or wind-scoured areas for safer skiing & climbing.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Wind slabs that formed Sunday night from 6 inches of snow plus another inch yesterday on a northwest wind are the avalanche problem today. Cold temperatures and moderate wind speeds suggest these wind slabs are likely to be more reactive than stubborn and could be found higher in the terrain below ridgetops. 

    Areas of most concern include the Headwall of Tuckerman Ravine and to a lesser extent the main gullies in the Gulf of Slides and Huntington Ravine. 

    Watch for wind slabs as smooth pillows of drifted snow formed in the top half of slide paths. You might also trigger an avalanche today where spindrift snow collects at angle changes in the terrain, typically near the bottom of slide paths. Look for plump, pyramid shaped aprons of snow as an indicator. With wind slabs of this size, frequent use of the Hand Shear Test can be an effective tool to determine how well the new snow is bonded to the bed surface and if careful, for finding shallow weak layers within the snow. 

Avalanche Discussion

Some uncertainty exists on the size and distribution of today’s wind slab avalanche problem. Yesterday’s Moderate hazard rating was based on 6 inches of snow Sunday, with another 2-4 inches possible yesterday. Snowfall yesterday amounted to just about 1 inch which removes some of the raw materials for the wind slab equation. 

Graupel was observed in eastern ravines on Sunday afternoon and may still exist in isolated areas, mostly terrain depressions where they can collect and pool. Watch for these ball-bearing like rimed particles to act as a weak layer buried under today’s wind slabs. Given the damp, old snow beneath, this weak layer is likely to stabilize quickly in the next day or two though keep it in mind as you may find trigger points in unusual places. 

Avalanche concerns today are limited to the recent snow. Warming and refreezing has worked to stabilize and in some places solidify the snowpack beneath the new snow. 

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.

Regioni coperte