Boletín de aludes

Central Sierra Nevada

Sierra Avalanche Center
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Peligro de aludes

Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
Desactualizado: este boletín caducó 8 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Areas of MODERATE avalanche danger will exist today at all elevations. A loose wet avalanche problem will develop quickly this morning in areas where a poor snow surface refreeze occurred last night. Avoid travel in or below avalanche terrain on slopes with marginally supportable to unsupportable wet snow conditions or on slopes where roller balls are occurring. This is the last avalanche advisory of the 2017/2018 season.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1

    Air temperatures were warm last night, generally in the 40s for most mid and upper elevation locations. A thin superficial refreeze will likely have occurred overnight on open slopes due radiational cooling under clear skies. Below treeline, the snow surface may not have refrozen at all last night under areas of dense forest canopy. The Carson Pass area was colder last night and may have had a bit better of a refreeze. Regardless of if overnight refreeze was poor or decent, rapid warming today will allow for a loose wet avalanche problem to develop quickly on all aspects at all elevations. Avalanche size up to D2 is possible (large enough to bury or injure a person).

    Monitor snow surface conditions as the day progresses. Pay attention to supportability of melt-freeze crust at the snow surface. Pick an area not compacted by previous tracks and punch a hole in the crust to gauge crust thickness. Compare surface crust thickness on open slopes to areas under dense forest canopy in order to get a sense of the overall strength of refreeze in the area. Once melt makes the surface crust marginally supportable to unsupportable, loose wet avalanches are possible. Human triggered roller balls are also a sign of potentially unstable snow. Avoid travel in or below avalanche terrain on slopes with marginally supportable to unsupportable wet snow conditions or on slopes where roller balls are occurring.

Avalanche Discussion

* Observations were made and received yesterday from Andesite Peak and Castle Peak (Donner Summit area). A weak overnight snow surface refreeze had occurred in the area with signs of loose wet instability present on E and NE aspects at 9:15 am.

* Snow cover continues to become thin to nonexistent in the lower elevations of the forecast area. Snow cover improves above 7,200'-8,000' depending on location. Numerous open creeks exist below 8,000'.

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