Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

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

In sintesi

Warm temperatures and clear skies will melt and loosen snow on all aspects and elevations today. Continuous melting overnight has increased the likelihood of triggering large wet slab avalanches today on slopes over 35 degrees in steepness. Deeper boot penetration, roller-balls, and glistening wet surface snow are good clues that the avalanche problem is immediate. 

Problemi valanghivi

  • Wet Slabs

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

    With overnight temperatures remaining above freezing in most locations, continuous melting of the snowpack will increase the likelihood of large wet slab avalanches. According to the Auto Road Vertical Profile Temperatures; all but the highest recording station on the summit of Mount Washington at 6288 feet, stayed above freezing. With anticipated rapid warming at all elevations today expect melting slabs to become unstable earlier this morning. Previously deposited wind drifted slabs that did not heat up yesterday will begin to melt today, and will be possible to trigger.

  • Loose Wet

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

    With recent snow at variable depths all across the three elevations zones, encountering loose wet snow today may be unavoidable. Yesterday, small wet point releases and roller balls were evident on sun exposed aspects. Skiers experienced heavy wet and deep boot-penetrating snow on these southerly slopes. As the lowest elevations are seeing temperatures near 55F degrees this afternoon, expect all aspects and elevations to have this avalanche problem at some point today.  

    Keep in mind this avalanche problem has the potential to add mass to a human trigger, increasing the likelihood of triggering a deeper wet slab at middle elevation. 

Avalanche Discussion

Wind blown snow and warm sunny skies allowed for good, but variable, skiing in Tuckerman Ravine yesterday. Northern aspects were slow to warm above freezing in the middle elevations, and the upper elevations stayed below freezing even during the heat of the afternoon. South aspects became warm rapidly as the sun was exposed to them, sending small wet loose avalanches downslope in the form of roller balls and point releases. Boot penetration was roughly calf to knee deep in the warm moist snow from melting, while northern aspects still held dry soft snow with similar depths in loaded locations.

Around 12:15 a pair of skiers entered Left Gully above a deposit of wind blown snow. The first individual dropped in on the skiers left side of the run and immediately triggered a wind slab avalanche. The slab was almost one foot deep at the crown, while the propagating crack initiated at their feet running a length of 100 feet across the terrain feature. At the time there was no one ascending the run and the avalanche ran uninterrupted over 1000 feet towards the ravine floor. The wind slab avalanche would be categorized: as a skier triggered; soft slab; size relative to path ⅗ & destructive potential ⅖ R3D2; at the old snow/new snow interface (SS-AS-R3-D2-I). The avalanche did not collide with anyone and flushed-out most of the wind deposited snow. Although at that time there was active loading from wind blown snow off the upper snowfields.

Thanks to everyone for taking 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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