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
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

Blowing and drifting snow near ridgetops will continue to deposit into cohesive slabs today. Weak snow underneath the recent storm snow may fuel instability in some locations. Move cautiously around avalanche terrain adjacent to recent avalanches, in areas where drifting snow is depositing, or where snow surface cracking is occurring.

Problemi valanghivi

  • Wind Slabs

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

    Winds out of the NE that accompanied yesterday's snowfall will remain out of the NE and increase in speed today and tonight. Areas of blowing and drifting snow near ridgetops will continue to deposit into wind slabs in near treeline and above treeline areas across SE-S-SW-W-NW-N aspects.

    Look for and identify where wind drifted snow is accumulating and expect to find it in less common areas due to the NE wind direction. Use clues such as blowing snow, freshly formed pillows of wind drifted snow, and snow surface cracking to identify where unstable snow may exist. Move cautiously around avalanche terrain where signs of potentially unstable snow are present.

  • Storm Slabs

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

    Areas of unstable snow are expected today in wind protected areas near treeline and below treeline. There are a couple of concerns at work here. First, the new snow that was deposited yesterday has surface hoar and/or graupel below it in some areas. Second, the low density recent storm snow will become a more cohesive slab as time passes. This is creating the classic slab over weak layer scenario. Avalanches may be fairly easy to trigger in some areas and could have wide propagation.

    Any wind protected areas where snow surface cracking is easily triggered are suspect for storm slab avalanches. Consider moving to low angle slopes and avoiding exposure to avalanche terrain in areas where snow surface cracking or recent avalanches are observed.

    (1/29/2023)

    An ECT with partial propagation on buried surface hoar. Just lacking a sufficiently cohesive slab. South of Carson Pass, near Charity Valley, CA

    Photo: SAC

Avalanche Discussion

  • Surface hoar that persisted to burial was observed below the new snow in some areas yesterday and may contribute to instability today.
  • Substantial amounts of graupel were observed in some areas during the early part of yesterday's snowfall and may contribute to instability today.
  • Avalanche activity today is expected to occur within the top 4 to 18 inches of the snowpack, failing at or above the recent old/new snow interface.
  • Below average air temperatures today and tonight may slow the process of stabilization.

Regioni coperte