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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Out of date — this forecast expired 10 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

A fast and powerful winter storm will impact our area starting this morning and continue through tonight.  Avalanche hazard will quickly rise to High as snowfall rates approach 3'' per hour later this morning.  Wind slab and storm slab avalanche problems will be very likely at all elevations throughout the region.  An avalanche warning has been issued for the forecast area until 7am Saturday morning.  Very dangerous avalanche conditions exist.  Travel in avalanche terrain is not recommended.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Certain
    Size
    2

    As the storm intensity increases throughout the morning, plenty of new snow will be available for wind transport to form new wind slabs.  Gale force SW winds with wind gusts up to 100mph are forecasted over ridges and peaks through today and tonight.  Wind slabs will quickly form this morning on NW-N-NE-E-SE aspects near treeline and above treeline and continue to build throughout the day.  Natural avalanches are likely and human triggered avalanches are very likely.  

    Travel in avalanche terrain is not recommended today.  Avoid avalanche runout zones.  Dangerous avalanche conditions will exist.

      

  • Loose Dry

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

    Snowfall intensity will increase early this morning and reach upwards of 3'' per hour through most of the mid day hours.  This fast moving winter storm could drop 1 to 2 feet of snow above 7000' today and tonight with more at higher elevations.  Storm slabs will become very likely on all aspects below treeline and near treeline as this new storm snow has difficulty bonding to itself and/or the old snow surface.  On shaded W-NW-N-NE-E aspects near treeline and below treeline the possibility exists for these storm slabs to fail on a near crust facet layer that exists on top of the Dec. 15 rain crust.  These avalanches could be larger in size, remotely triggered, entrain more snow, and have much higher consequences.

    Travel in avalanche terrain is not recommended.  Natural triggered avalanches are likely and human triggered avalanches are very likely.  Very dangerous avalanche conditions exist.  Avoid avalanche runout zones.  

Avalanche Discussion

Observations were made and received at Ophir Peak (Mt. Rose area), Castle Peak (Donner Summit area), and Forestdale/Frog Lake Ridge (Carson Pass area).  Unconsolidated surface snow was found above a supportable base in most areas.  Near surface facets and near crust facets above the Dec. 15 rain crust existed in all wind protected areas that had not seen wind scouring.  Observations showed concern as to the strength of these near crust facets and how they will react to additional load.  Temperatures were warming with increasing winds throughout the day. 

Regions covered