Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Continued blowing and drifting of snow on the ground has created unstable avalanche conditions on some slopes where blowing snow has accumulated.  Exercise caution near or below slopes with visible blowing snow, with cornice features, or where recent avalanches have occurred.

Problemi valanghivi

  • Wind Slabs

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

    Moderate to gale force SW winds are blowing, drifting, and redistributing snow on the ground. This has created new wind slabs in areas where this blowing snow has deposited, mainly above treeline and near treeline on NW-N-NE-E-SE aspects. One relatively small natural wind slab avalanche was reported yesterday on an E aspect in near treeline terrain near Poulsen Peak in the Pole Creek area. We also received some reports of swirling winds yesterday that created irregular patterns of drifting, and sometimes further downslope than anticipated.

    Identify and move cautiously around slopes where there is visible blowing snow, slopes that are below cornice formations, have a rippled wind textured snow surface, or are near any areas where snow surface cracking is occurring. 

Avalanche Discussion

*Snowpack data suggests that triggering a persistent slab avalanche on old layers of weaker snow 4 to 5+ feet deep in the snowpack is unlikely due to isolated lingering weak layer distribution and difficult (stubborn) triggering. Forecast guidance directs removing persistent slabs as an avalanche problem once likelihood decreases to unlikely. Unlikely is not impossible so the savvy things to do right now as a backcountry traveler are to avoid traveling near exposed rocks where the old weak layers could be closer to the snow surface and avoid creating large impacts on slopes from actions such as jumping off of rocks, cliffs, or cornices.

*Surface hoar has been observed in numerous locations around the forecast area. The question for this potential future weak layer is if it persists to burial or is destroyed by wind and warming prior to the next round of snowfall tomorrow evening. Some surface hoar was observed to become buried yesterday under drifting snow near the junction of wind exposed and wind sheltered terrain in the Carson Pass area. In the more wind exposed areas, it had been knocked over prior to burial.

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