Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
Open full map
Non aggiornato — questo bollettino è scaduto 13 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

HIGH avalanche danger exists on slopes steeper than 30 degrees in near and below treeline terrain on NW-N-NE aspects due to new heavy snow slabs sitting on top of persistent weak layers. Natural and human triggered avalanche are very likely on these slopes today. CONSIDERABLE avalanche danger exists on the wind loaded NW-N-NE-E-SE aspects in near and above treeline terrain due to the pressence of newly formed wind slabs on slopes 35 degrees and steeper. MODERATE avalanche danger exists on all other aspects.

Travel in, around, or near avalanche terrain is not recommended today.

Problemi valanghivi

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2

    Natural and human triggered persistent slab avalanches are very likely today on near and below treeline NW-N-NE aspects. New slabs made of heavy snow that has fallen since yesterday now exist on top of a snowpack that consists of several persistent weak layers on these aspects. The snowpack could barely support itself before the new load arrived. As more snow falls today the slabs will grow in size and extent. Heavy slabs on top of persistent weak layers create very serious avalanche conditions. These kind of avalanches can be triggered from a distance or from "safe" slopes connected to steeper terrain. These avalanches could involve the entire snowpack. These conditions look more like a typical Colorado snowpack than a Tahoe snowpack. Don't let habits and familiarity or "powder-fever" dictate decisions today. These unusual conditions require extra caution and superb travel skills. Travel in, around, or near avalanche terrain is not recommended today.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2

    New snow and strong winds have created wind slabs on the near and above treeline NW-N-NE-E-SE aspects. As snow and wind continue today these slabs will increase in size and extent. Human triggered avalanches involving these wind slabs are likely and natural avalanches are possible. On the NW-N-NE aspects where these slabs exist above the old persistent weak layers natural and human triggered avalanches are very likely, and they will behave more like the persistent slabs discussed above.

Avalanche Discussion

Yesterday near Red Lake on Carson Pass, snow level hovered around 8400 ft. for most of the day. Due to the steady rain, free water had penetrated to the bottom of the shallow snowpack. In this area yesterday, the snowpack consisted of several layers of wet, weak, unconsolidated facets. The snowpack could not even support a person on skis and each time I weighted my skis I sank to the ground. Some skier triggered cracking started to occur on N-NE aspects yesterday afternoon as the snowpack weakened. Snowpit tests confirmed this weakening with all results indicating a snowpack that could barely hold itself up and some results showing that fractures could travel through the buried persistent weak layers.

Regioni coperte