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

Anticipate encountering unstable slabs of wind drifted snow in wind exposed areas near treeline and above treeline today. MODERATE avalanche danger exists above treeline and near treeline with LOW avalanche danger below treeline.

Problemi valanghivi

  • Wind Slabs

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

    Winds shifted back to the SW yesterday morning and became gale force last night. This will have scoured and drifted any available snow in wind exposed areas, forming wind slabs in lee areas. Wind slabs composed both of drifted older snow and drifted new snow today are expected near treeline and above treeline on NW-N-NE-E-SE aspects. Avalanche size is expected mainly at D1 with size D2 possible in the more heavily wind drifted areas.

    Wind, new snow, and potentially decreased visibility at times may challenge group communication today. Identify potentially unstable wind slabs by looking for blowing and drifting snow, recent cornice and wind pillow formations, lee areas of smooth looking slope, and snow surface cracking. When areas of concern are identified, make a plan within your group for how to move around these areas with an increased margin of safety.

Avalanche Discussion

* Several small (size D1) intentionally skier triggered wind slab avalanches occurred on Jan 8 & 9. These occurred along the Sierra Crest in the northern portion of the forecast area in above treeline and near treeline terrain on N-NE-E aspects.

* Weak snow in the upper snowpack (facets and low density DFs) around the Dec 12 and Jan 4 rain crusts are failing in snowpit tests when placed under an artificial new snow load. This is a weak layer of concern for future storms this week. Check out the loaded PST video from Jan 10.

* The middle and lower portions of the existing snowpack are consolidated, well bonded, and in good condition to handle new snow loading.

Regioni coperte