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
Non aggiornato — questo bollettino è scaduto 10 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger exists on all aspects and elevations today due to newly formed wind slabs on wind loaded slopes above 8000 ft. and rain on snow creating loose wet snow instabilities on slopes below 8000 ft. Human triggered avalanches will be possible today.

Expect the avalanche danger to rise quickly as the next storm impacts the region tonight. Periods of HIGH avalanche danger may occur tonight as natural wind slab avalanches and storm slab avalanches become likely after midnight. 

Problemi valanghivi

  • Wind Slabs

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

    New snow and wind during the night allowed new wind slabs to form on wind-loaded and cross-loaded slopes that received snow instead of rain. These wind slabs will continue to grow as more snow and wind impact the forecast area today. While many of these wind slabs may remain relatively small, some of these slabs could measure 18 to 36 inches in depth in heavily wind loaded areas. These wind slabs may have a layer of lighter, colder, weaker snow that fell during the night at their base. Human triggered wind slabs will be possible today on wind loaded N-NE-E aspects and cross-loaded NW and SE aspects above 8000 ft. in near and above treeline terrain where more of the precipitation has fallen as snow. 

    As the second storm impacts the region tonight, wind slabs will quickly become large, and natural avalanche activity involving these large new wind slabs will be likely after midnight tonight.  Storm slab avalanches may also occur in non wind-loaded areas tonight due to the intense snowfall rates and changing conditions during the storm. 

  • Loose Wet

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

    Rain on snow may trigger more loose wet avalanche activity below 8000 ft. today. The NW-N-NE aspects will represent the best places to find loose wet snow avalanches since the snow on these aspects has not transitioned to corn snow, and it has not developed good drainage channels. Small loose wet snow instabilities like roller balls, pinwheels, and point releases should represent the majority of the loose wet snow problems today, but some larger loose wet snow avalanches may occur on those northerly aspects. Smaller more isolated loose wet snow instabilities may still form on isolated terrain features on the E-SE-S-SW-W aspects below 8000 ft. 

Avalanche Discussion

Yesterday observations from Donner Ridge (Donner Summit area) and Incline Lake Peak (Mt. Rose backcountry) showed a snowpack that should handle new snow loading well. Below the surface snowpit tests did not find any signs of instability. On the snow surface, observations showed warm wet snow on all aspects up to about 9000 ft. on Incline Lake Peak and up to the summit of Donner Ridge. Some small human triggered pinwheels did occur on NE-ENE aspects below 9000 ft. on Incline Lake Peak. 

Regioni coperte