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
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 11 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger remains MODERATE for all elevations and aspects on slopes 37 degrees and steeper due to another suspected poor overnight snow surface refreeze and subsequent loose wet avalanche concerns. Continuous snow cover on SE-S-SW-W aspects sufficient to allow for avalanche activity exists only in isolated areas.

Problemi valanghivi

  • Loose Wet

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

    A second night of cloud cover and well above freezing air temperatures is once again expected to have allowed for a poor to nonexistent overnight snow surface refreeze. In areas where breaks in cloud cover allowed for a short window of radiational cooling, any snow surface refreeze that did form is expected to be superficial, thin, and weak. As daytime warming progresses, areas of wet surface snow will become widespread in the vast majority of areas. The lack of snow cover remaining on most SE-S-SW-W aspects will limit instability that forms today on those aspects to the isolated areas of continuous snow cover. Of the NW-N-NE-E aspects with continuous snow cover, E aspects will hold the greatest amount of wet snow with carry over from yesterday and the day before that did not refreeze last night. Potentially more problematic areas of wet snow will exist on NW-N-NE aspects where the snowpack remains more transitional with less previous melt-freeze. Human triggered loose wet avalanches are possible today on slopes 37 degrees and steeper. Keep in mind that secondary terrain hazards such as cliffs and terrain traps below hold the potential to greatly magnify consequences of an avalanche that would otherwise be too small to bury or injure a person.

Avalanche Discussion

Observations made yesterday on Tamarack Peak (Mount Rose area) revealed that cloud cover and above freezing air temperatures overnight had allowed for only a minimal, weak overnight snow surface refreeze to occur. Boot penetration of 8 inches into wet snow was observed in non-compacted areas at the trailhead at 8,600' at 9:45 am. Previously compacted areas of traditional skin track placement and heavily trafficked slopes such as Hourglass and Proletariat were much more supportable than the vast majority of lesser trafficked surrounding areas. Ski cuts on the Far East Ridge of Tamarack Peak (N aspect, 9,100') produced small amounts of roller balls and pinwheels that reached up to 18 inches in diameter at 11:30 am. An upper snowpack structure of 2 to 4 inches of surface wet snow over old snow not yet affected by melt-freeze was noted in many areas on northerly aspects, including the Far East Ridge. Well established melt-freeze conditions were noted on the aspects that generally receive more sun exposure.

Regioni coperte