Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 11 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Pockets of MODERATE avalanche danger exist above treeline on all aspects on slopes 35 degrees and steeper due to lingering wind slabs. Near treeline and below treeline avalanche danger is LOW on all aspects. Isolated areas of unstable wind slab may remain near treeline, especially in complex terrain. LOW danger means that human triggered avalanches have become unlikely and areas of instability are isolated, not that avalanches will not occur.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Strong winds first from the SW, then from the NE over the past 48 hours created visible blowing snow over the high terrain. Significant redistribution of snow on the ground has occurred since the storm. Wind scouring has occurred in many areas near treeline and above treeline on N-NE-E aspects. Pockets of wind slab have been left behind, especially in complex terrain in gullies and around rock buttresses. New wind slabs have formed on SE-S-SW-W-NW aspects. Keep in mind that after the recent winds, if a near treeline or above treeline area looks nicely filled in, it is likely a wind slab. Keep early season excitement in check and fully evaluate conditions before committing.

Avalanche Discussion

Observations made yesterday on Tamarack Peak (Mount Rose area) showed significant amounts of blowing snow, wind scouring, and redistribution of snow on the ground. Remote sensors across the forecast area are indicating around 2 inches of settlement has occurred within the recent storm snow in wind protected areas. This settlement, recent snowpit tests, informal observations, and time for recent new snow to bond to the often faceted old snow surface has reduced concerns for storm slabs.

If any of the coldest, shadiest, most wind protected N-NE aspects still hold storm slab instability near or below treeline it will be very isolated instability, not warranting specific mention of storm slabs as an avalanche problem. In terms of snowpack evaluation, lingering storm slabs will present as cohesive recent new snow on top of and poorly bonded to older near surface faceted snow below.

Regions covered