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
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Non aggiornato — questo bollettino è scaduto 9 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

As the day warms up, the avalanche danger will increase to MODERATE due to the potential for loose wet avalanches.  A few isolated persistent slabs may also linger on some near and below treeline slopes, especially in the Carson Pass and Ebbetts Pass areas. 

Problemi valanghivi

  • Loose Wet

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

    Partly cloudy skies with some sun and warmer temperatures should allow loose wet instabilities including roller balls, pinwheels, and point release avalanches to become possible on steep sun-exposed slopes again today. The stronger winds may help dimish the chances of larger loose wet instabilities. Most of these loose wet instabilities should not entrain enough snow to bury a person, but they could knock a person over or push a person into terrain where collisions or a fall would have serious consequences.

  • Deep Persistent Slabs

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

    Persistent slabs are unlikely across most of the forecast area; however, isolated persistent slab avalanches may remain possible in the Carson Pass and Ebbetts Pass areas. If a persistent slab avalanche does occur, the failure layer would likely be loose weak snow near a crust 8 to 18 inches below the surface (near crust facets). Persistent slabs could involve enough snow to bury or injure a person (size D2 with some potential for an isolated D3).  Observations including snowpit tests and some snowmobile triggered shooting cracks over the last few days continue to indicate that this layer remains weak on some near and below treeline NW-N-NE facing slopes in the Carson Pass and Ebbetts Pass areas. Significant uncertainty still remains as to how widespread this problem may be.

    Look for and avoid avalanche terrain in any areas where snow surface cracking, snowpack collapse/whumpfing, and/or unstable snowpit test results are occurring.

Avalanche Discussion

* Snowpit tests targetting the near crust facet layer yielded unstable results on Elephants Hump (Carson Pass area) yesterday. This data is consistent with other signs of instability concerning this layer in the Carson Pass area and Ebbetts Pass area over the last few days. Snowpit data from Ophir Peak (Mt. Rose backcountry) revealed the presence of this layer, but did not show signs of current instability. 

* Observations from National Geographic Bowl (Granite Chief Wilderness) and Castle Peak (Donner Summit) both showed a well-bonded snowpack.

* Wet, sticky snow existed on all aspects below 9000 ft. on Elephants Hump, below 8500 ft. on Ophir Peak, and on the lower elevations of Granite Chief and Castle Peak. Roller balls and pinwheels occurred on N-NE-E aspects on Elephants Hump, on N-NE aspects of Ophir Peak, and all aspects on the lower elevations of Granite Chief.

* Observers reported large cornices and wind-loaded slopes on Castle Peak and Granite Chief but did not find lingering signs of instability concerning the wind slabs. They avoided testing the large cornices.  

 

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