Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

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

In sintesi

Avalanche and weather conditions are dangerous today and tonight. New snow, and several inches of rain will create a very unpredictable snowpack. Very high wind speeds, rain, and plummeting temperatures late in the day make mountain travel especially hazardous.

Problemi valanghivi

  • Wet Slabs

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

    As of 5am, 8 inches of new snow has fallen at middle elevations. Once temperatures rise this morning, the new snow will be soaked by several inches of rain and could have the potential to avalanche naturally. Generally speaking, rain on a dry snowpack quickly decreases stability by adding weight and further eroding weak layers within. 

    Today, the recent snow is already fairly wet, has fallen on a cold bed surface, and has been subject to hours of very high wind speeds resulting in a stable layer of snow that is likely to withstand the rain. However, given the volume of incoming rain and the unpredictable nature of wet slabs, extra caution is advised.  With rainfall ending and temperatures dropping, the likelihood of wet avalanches will diminish overnight due to the snowpack refreezing.

  • Wind Slabs

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

    Watch out for additional snow drifting and forming new wind slabs once temperatures drop below freezing and rain turns back to snow later today and overnight. With high wind speeds, new slabs are likely to be stubborn to a trigger and potentially well bonded to the refreezing snowpack. Very high wind speeds swinging west, timing of dropping temperatures aligning with remaining precipitation will all play a role in determining distribution of this avalanche problem.  

Avalanche Discussion

Today’s weather forecast is unusual in that there’s significant amounts of water available in this system. As of last night, 3-4 inches of water was forecast to fall as snow, rain or mixed precipitation. While temperatures were initially forecast to be on the warmer side, recent models suggest colder temperatures keeping the summits just barely at or below freezing. While this cooler trend does help boost snowfall totals at upper elevations, precipitation at middle and lower elevations will likely be more rain than snow. 

It should be noted that temperature is a significant variable today, directly affecting snow totals and even a slight temperature swing  in either direction can lead to much higher or much lower amounts of new snow. As a result, temperatures will play a role in determining the size of the avalanche problem. Meaning, with so much water available, colder temperatures could easily boost snow totals which will increase the overall avalanche hazard.

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

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