Avalanche forecast

Continental

Valdez Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The avalanche hazard is moderate at all elevations.  Human triggered avalanche are possible 1-2 feet in depth.  Natural avalanches are unlikely.  Instabilities may exist in steep terrain and on specific terrain features that have been loaded by wind.  Watch for signs of instability such as shooting cracks and collapsing.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Southeast winds are forecasted to become moderate this afternoon in response to a low pressure system approaching the area  that is expected to deliver heavy snow overnight into Sunday morning.  4-6 inches of new snow fell along the coast Friday evening that will add to the already abundant amount of snow available for transport.  Pay attention to the affects that wind is having on the snow surface today and signs of previous wind loading.

    Human triggered avalanches are possible 1-2 feet in depth on slopes that have recently been loaded by wind.  Wind slabs may exist on a variety of aspects due to changing wind direction over the last couple days.

    Wind slabs will often have a pillowed look and may have rippled texture on the surface.  Stiffer snow over soft is a sign of wind slabs.  Shooting cracks are a sign that instability exists.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    There is the potential that facets that have formed beneath the Turkey day crust could be a concern for the intermountain and continental zone below 4000'.   This layer is buried by 3 or more feet of snow.

    It is unclear at this point if this layer is a concern in these areas, but is certainly worth investigating.  Dangerous avalanches would result if this layer were to fail.  Digging snowpits is the best way to assess this potential weak layer.  Since this layer is deeply buried, it is very possible that signs of instability will not exist.

    This layer has been listed as an avalanche problem due to uncertainty and its destructive potential. 

     

Avalanche Discussion

4-6 inches of low density snow fell along the coast yesterday evening.  It is unclear if Thompson Pass picked up this snow as well,  snotel sites are not showing new snow from yesterday, although these weather stations are not always reliable.  

This new snow will add a bit of stress to storm slabs from12/11-12.   A significant change in stability is not expected with the addition of new snow, although areas where the new snow is being redistributed by wind will be a concern.   Storm slabs from 12/11-12 have been found to be right side up with good bonding observed at the new/old interface.  Instabilities may still exist in wind loaded areas and steep terrain, especially on convex slopes or those that are unsupported.  

There is a significant amount of snow available for transport.  This will allow for wind slabs to easily form where wind redistribution is occuring that may be sensitive to human triggeres on slopes steeper than 30°.  Watch for signs of wind loaded snow and avoid these areas where they exist on slopes steeper than 30° epsecially when signs of instability are present.  

It is possible that the thansgiving day crust may be a deep persistent weak layer concern in the intermountain and continental zone.  The potential for this is unclear at this point, digging in the snow will be the best way to assess this potential problem.

Moderate SE winds will build today as the next storm approaches our area.  Heavy snowfall is expected overnight with 8-16 inches of snow possible at upper elevations and the potential for rain at low elevations.

Regions covered