Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Large avalanches remain likely in areas where wind-blown snow has filled in slopes near ridges, gullies, and open areas. Large overhanging waves of snow (cornices) along ridges may also crash down on these slopes. As the day warms up, avalanches of wet, loose snow may be possible on sunny slopes sheltered from wind. Staying alert and on top of the changing conditions will prove challenging today, opting for lower angle, low consequence terrain is a good idea.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Strong SW winds have been blowing snow onto slopes downwind of ridges, onto open slopes, and into gullies and will continue to do so today. The largest wind slabs will exist in near and above treeline terrain, but some wind slabs may also lurk in open areas below treeline due to the strength of the winds. Several wind slab avalanches occurred yesterday, and wind slab avalanches large enough to bury or injure a person remain likely today. The strong March sunshine could also make triggering these wind slabs easier on sunny slopes and cause the large and fragile cornices looming over many slopes to weaken or fail. 

    Blowing snow, ripples on the snow surface, cornices above a slope, drifted snow, and other wind-created textures can also help identify where wind slabs have formed. Recent avalanche activity and cracking in the snow represent obvious clues that unstable wind slabs lurk nearby. Travel plans prioritizing areas sheltered from the wind and avoiding wind-loaded slopes, areas below large cornices, and avalanche run-out zones can help reduce exposure to the wind slab problem.

    (3/15/2025)

    This wind slab avalanche may have been triggered by people based on the tracks near the avalanche. It is in a wind-loaded area just above Snow Shed Wall on Donner Summit. 

    Photo: Sierra Avalanche Center

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    The strong SW winds should keep the snow cooler on wind exposed slopes and prevent unstable wet snow from forming in many places. However, wind sheltered areas with direct sun exposure may experience enough warming from the strong March sun and above freezing temperatures for wet loose avalanches to become possible. Wet loose avalanches could entrain enough snow to knock a person over or push them into a terrain trap that magnifies the consequences of an avalanche. They may even involve enough snow to bury or injure a person on a larger slope since they entrain more snow as they move downhill.

    Roller balls, pinwheels, and feeling the snow change from cold and soft to wet and heavy provide clues that unstable wet snow exists. Traveling on less steep terrain represents one way to enjoy soft, wet snow and reduce exposure to this problem. Another way involves timing your travel to move to colder aspects or exit the area before the snow gets mushy and wet. 

Regioni coperte