Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wet snow instability continues with rain soaked snow, poor refreeze conditions last night, and well above freezing air temperatures today.  Small wet snow avalanches are possible on all steep slopes with the potential for large and destructive avalanches in isolated areas. Move cautiously in or below avalanche terrain and consider avoiding avalanche terrain near any areas where a snowpack collapse or audible whumpfing noise occurs.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    This is a low likelihood, very high consequence avalanche problem today. It remains possible to trigger a large to very large avalanche in isolated areas. If you encounter a snowpack collapse or an audible whumpf, steer clear of avalanche terrain in the vicinity. Unfortunately, signs of slab instability may not precede the triggering of a wet slab avalanche given today's conditions. The best bet is to make conservative terrain choices.

    The recent rain on snow event reduced the height of the recent storm snow dramatically in many areas. Weak layers in the snowpack, such as the remains of the Feb 10 faceted snow layer, are much closer to the snow surface. In some areas, this layer is only half as deep in the snowpack as it was before the rain event, even at upper elevations. Snowpit test results suggest that despite rainwater reaching this weak layer, it can still collapse and propagate. More time is needed for this layer to gain strength and refreeze.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Wet snow abounds on all aspects and at all elevations. Move cautiously around avalanche terrain in areas where you can trigger rollerballs and/or pinwheels. You could trigger a wet loose avalanche on steeper slopes in locations where you sink more than a few inches into a wet snow surface.

    Cloud cover for much of last night, combined with above freezing air temperatures, is expected to have allowed for very little to no overnight snow surface refreeze. Above-average air temperatures and increasing solar input will produce more free water in the upper snowpack today. Wet loose avalanches could be triggered much earlier in the day today than if a snow surface refreeze had occurred last night.

Avalanche Discussion

The recent rain event decreased snow depths dramatically, especially below 7,500' and on southerly aspects. This has created a hazard situation similar to early-season coverage in some areas.  Deep open holes, open creeks, and ponded water linger in low-lying areas, especially below 8,000'.

The avalanche that occurred on Tuesday, February 17, at the Frog Lake/Castle Peak area is a major blow to our community, and the human toll is immeasurable.  Our condolences go out to all those affected by this tragedy.  We have an avalanche observation posted here:  Perry Peak near Frog Lake/Castle Peak. We will update that page with any additional information that becomes available.

Regioni coperte