Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 7 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger continues above treeline and near treeline due to a variety of difficult to trigger hard and soft wind slabs. LOW avalanche danger exists in wind protected areas below treeline. 

Problemi valanghivi

  • Wind Slabs

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

    SW winds have drifted snow and deposited it as wind slabs in above treeline and near treeline terrain. Wind slabs ranging from soft slab to hard slab are widespread on NW-N-NE-E-SE aspects. Old snow on the ground that is still available for drifting is minimal. Older wind slabs formed during the Dec 18 wind event are gaining strength.

    At this point, wind slabs exist in most all lee areas near treeline and above treeline but are difficult to trigger. Any avalanches that occur today will most likely be isolated and in an area surrounded by seemingly good stability. Avalanche size up to D2 remains possible. While triggering one of the older hard wind slabs over softer near surface facets from Dec 18 has become unlikely, the consequences of doing so remain elevated.

    Use the clues of recently wind drifted snow to identify areas of wind slab and adjust routes accordingly. Recently wind drifted snow exists below cornices, at and below rounded wind pillows, and where indicated by wind scouring vs deposition patterns along ridgelines.

Avalanche Discussion

Recent observations have shown a variety of hard and soft wind slabs in near treeline and above treeline terrain. In some areas, especially near treeline, wind slabs sit on top of a soft layer of near surface facets. Ongoing strength gains for these older wind slabs on near surface facets have been observed day to day. No new avalanches have been reported since Dec 18. Light to moderate amounts of drifting snow was observed yesterday along ridgelines. Wind protected areas below treeline continue to hold unconsolidated surface snow on shaded northerly aspects (near surface facets). Snowpit tests looking deeper into the snowpack have not identified any problematic weak layers beyond the wind slab over near surface facets structure.

Regioni coperte