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 today in wind exposed areas near treeline and above treeline. 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

    Small slabs of wind drifted snow that were easily triggered as size D1 wind slab avalanches yesterday are expected to remain unstable today. Additional snowfall with wind this morning will allow for more drifting and wind slab formation today. Anticipate encountering unstable wind slabs in wind exposed near treeline and above treeline terrain today, mainly on NW-N-NE-E-SE aspects. Expect avalanche size today mostly at D1 with size D2 possible in the most heavily wind drifted areas.

    Identify where unstable wind slabs may exist and move around them with caution. Areas with pillows of wind drifted snow, slopes below cornices, and any smooth looking slopes in wind exposed areas are suspect. Human triggered snow surface cracking is a sign of unstable snow. Communicate what you see within your group. Listen to the concerns of others and include them in group decision making.

  • Wet Slabs

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

    Small loose dry avalanches (sluffs) may occur today in steep wind protected areas below treeline. Recent new snow is low density and has been slow to bond to old snow surfaces. On a regional scale, this avalanche problem is unlikely today and limited only to areas that have accumulated a few inches or more of new snow yesterday and today. 

Avalanche Discussion

* Small (size D1) wind slabs were easy to intentionally trigger yesterday in the Mt. Judah (Donner Summit) and Silver Peak (Pole Creek) areas. These small avalanches occurred in near treeline terrain on N-NE-E aspects where wind drifted snow had deposited. Crown size ranged from 4 to 8 inches. These areas had received about 2 inches of new snow.

* Further south in the Echo Summit area new snow was minimal at just 1 inch and did not allow for the formation of unstable wind slabs.

* There is faceted snow in the upper snowpack on NW-N-NE-E aspects, mainly around the thin Jan 4 rain crust and to a lesser extent around the thicker Dec 12 rain crust. Both of these layers are in a monitoring state with ongoing snowfall events in the weather forecast.

Regioni coperte