Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 8 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

LOW avalanche danger continues this morning for all elevations. Following the onset of snowfall, an increase to CONSIDERABLE avalanche danger will occur at all elevations this afternoon and continue through the overnight hours. Wind slab and storm slab avalanche problems will develop.

Problemi valanghivi

  • Wind Slabs

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

    A wind slab avalanche problem will form quickly this afternoon following the onset of snowfall. The vast majority of wind slabs will form near treeline and above treeline on NW-N-NE-E-SE aspects and to a lesser extent in other locations including wind affected areas below treeline. Identify and travel around the edges of areas where wind drifted snow is depositing in avalanche terrain, especially near cornice features and wind pillows.

    In Sierra Crest locations where weak snow and thin crusts have been observed within the top 4 to 18 inches of the existing snowpack, additional travel considerations will become warranted as this storm cycle progresses. The collapse of these weak layers below the old snow surface may allow for wind slab avalanches to take on some persistent slab characteristics, failing wider than typical, possibly wrapping around corners and across adjacent avalanche paths all at once. As these areas of higher uncertainty develop, give wind slabs a wider margin of safety than normal.

  • Loose Dry

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

    A storm slab avalanche problem may form this evening and during the overnight hours as snowfall rates of 1-2" per hour create for rapid accumulation in wind protected areas. Storm slabs could form on any previously snow covered slope in below treeline or near treeline terrain.

    In areas where snow surface cracking occurs while making fresh tracks either uphill or down, identify and move around the edges of avalanche terrain.

Avalanche Discussion

* Recent observations from along the Sierra Crest indicate questionable ability for the upper snowpack layers consisting of weak facets and thin crusts to support new snow loading.

* The snowpack in the Mt. Rose area (Carson Range) lacks these crusts and appears in decent condition to handle new snow loading. Shallower, weaker snow has been noted further south along the Carson Range closer to Freel and Jobs Peaks.

* Recent gale force NE wind and warming events have left behind variable snow surface conditions including firm wind packed, firm wind scoured, exposed ice, melt freeze crust, and pockets of soft unconsolidated snow. In many locations, these different conditions exist in close proximity to one another.

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