Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

The hazard will rise to HIGH avalanche danger today. Large natural avalanches will become likely and human triggered avalanches will be very likely today and tonight. Rain on snow, heavy snow, and gale force winds will create a complicated and dangerous mix of wind slab, storm slab, and loose wet avalanche problems at all elevations. Travel in, near or below avalanche terrain is not recommended. Rain on snow could also cause dangerous roof-avalanches as roofs still holding snow unload. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2

    Gale force SW winds and new snow will form new wind slabs on top of existing wind slabs. The largest wind slabs should exist on NW-N-NE-E-SE aspects in near and above treeline terrain above 8000 ft where the most new snow accumulates. Wind slabs will also exist on wind-loaded slopes at lower elevations and in some exposed below treeline terrain due to the strength of the winds. Large natural and human-triggered wind slab avalanches will become very likely today and tonight. In areas where rising snow levels allow rain to fall on wind-loaded slopes, wind slab avalanches could involve wet snow and release more easily.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2

    Rising temperatures and intense snowfall, as well as some existing weaknesses in the snowpack, will cause storm slab avalanches to become very likely today and tonight as well. Storm slab avalanches could occur on any aspect with slopes steep enough to slide. Most storm slabs would involve the newest storm snow but some could entrain older storm snow especially in lower elevation areas on E-SE-S-SW aspects where the older storm snow rests on a thin crust. Like the wind slabs mentioned above rain falling on snow would make storm slabs easier to trigger and could cause them to entrain wet snow and result in larger avalanches.  

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2

    In addition to exacerbating the avalanche problems mentioned above, rain falling on snow will make widespread loose wet avalanche activity very likely. Loose wet avalanches could entrain significant amounts of snow today and tonight and become large enough to bury or injure a person. 

Avalanche Discussion

* A small wind slab avalanche occurred yesterday in the CHP chutes on Hwy 89 and caught a party who was skinning up. No one was injured. 

* A human-triggered avalanche occurred in less-exposed, lower-elevation terrain on a SE aspect in the burned area near Myers. This slide partially buried a party of 3. It may have failed on a weak layer near a sun crust that formed just before the most recent storm. No injuries were reported.

* Snowpit data from an E aspect above Crystal Bay found a weak layer near a thin crust below the most recent storm snow. Snowpit tests on this layer showed signs of instability that match with the avalanche reported in the Meyers burn area. Snowpit data from a more sheltered SE aspect on Scott's Peak and on a higher elevation SE aspect on Hidden Peak did not find this layer.

* Observations from Centerville Peak, Hidden Peak, Andesite Peak, Scott Peak, and Chocolate Peak all found widespread blowing snow and some wind slab formation. In some areas, these firm wind slabs remained stubborn and hard to produce signs of instability in and in others skier triggered cracking did occur on test slopes. 

* Widespread blowing snow could be seen all along the Sierra Crest and in the Carson Range all day yesterday.

Regions covered