Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

MODERATE avalanche danger will exist in near and above treeline terrain due to a wind slab avalanche problem.  Human triggered wind slab avalanches remain possible.  Low avalanche danger will continue in protected below treeline terrain.  Avalanche danger is expected to dramatically increase this evening.  This forecast is good for 12 hours and will be updated by 7pm.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    SW winds along with new snow today will continue to build wind slabs and cornices on NW-N-NE-E-SE aspects in near and above treeline terrain.  Gale force SW winds have been transporting snow and scouring windward areas for over 36 hours.  Snow available for transport is becoming limited until additional new storm snow picks up this morning.  Newly forming wind slabs along with continued building of existing wind slabs and cornices are expected throughout the day.  Wind slab avalanches up to size D2 (large enough to bury or injure a backcountry user) are possible.

    Avoid steep wind loaded slopes and areas below large cornices.  Blowing snow, cornice formation, and wind pillows will indicate where wind slabs may exist.  Make a travel plan with your group that avoids these specific wind loaded terrain areas.   

Avalanche Discussion

*  A small natural wind slab avalanche (D1) was reported on the east bowl of Mt. Judah (Donner Summit area) in open above treeline terrain.  A small skier triggered wind slab avalanche (D1) was unintentionally triggered on the NW side of Castle Peak (Donner Summit area).  In Johnson Canyon (Donner Summit area) an intentionally triggered wind slab avalanche failed on a small test slope.

*  Strong to gale force winds reported throughout the forecast region with intense blowing snow at most locations.  Areas of firm exposed crusts are present in many wind scoured locations.

*  Snowpack tests targeting the Feb 14 rain crust at Polaris Point (Carson Pass area) showed sudden planar results on a graupel layer buried 120cm down on top of the rain crust with the Deep Tap test.

Regions covered