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 10 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Areas of MODERATE avalanche danger linger near and above treeline due to old wind slabs. Below treeline, LOW avalanche danger exists. Avalanche activity has been reported in isolated areas each of the past two days.

Problemi valanghivi

  • Wind Slabs

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

    Old wind slabs may remain unstable in isolated areas on all aspects above treeline and on NW-N-NE-E-SE aspects near treeline. Evidence of instability gathered through informal observations and snowpit data has been limited at best, yet isolated avalanche activity continues to occur. The failure layer has not been confirmed in any of the avalanches that occurred over the past two days. Weak faceted snow that formed in the upper snowpack since Dec 15 has been noted in some areas and may be playing a role in the ongoing instability.

    Take home point: Avalanches continue to occur in isolated areas. Don't expect signs of instability to present readily, but rather remain elusive. Any additional avalanches that occur will likely take backcountry travelers by surprise. For this reason, don't allow travel partners to get sloppy by grouping up in runout zones, too close to the slopes above or by relying on marginal islands of safety for protection.

Avalanche Discussion

An avalanche was reported the have occurred yesterday during the late morning hours on Mount Houghton (Mount Rose area) in a SE aspect gully known for cross loading by both SW and NE winds. This avalanche overran previous tracks, much like the avalanche reported on Sunday.

Observations made and received yesterday from Castle Peak (Donner Summit area), Steven's Peak (Carson Pass area), and on Relay and Tamarack Peaks (Mount Rose area), showed that signs of instability were very limited. Occasionally but not always, snowpit tests have pointed to some potential instability in the upper portion of the snowpack. Data is limited, but newly formed facets have been observed on top of the Dec 15 rain crust in some but not all areas. In the highest elevation areas (above ~9,700') where the Dec 15 rain crust is absent, newly formed facets have been observed within the lower portion of the recent storm snow.

Regioni coperte