Avalanche forecast

Continental

Valdez Avalanche Center
View on map

Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche hazard is Considerable at all elevations.  Heavy snowfall overnight along with rising temperatures and moderate to strong southeast winds have created elevated avalanche hazard.  Human triggered avalanches are likely 2-3 feet in depth and natural avalanches are possible today.

Avalanche forecasts are issued Wednesday-Sunday.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2

    Thompson Pass received 20 inches of snowfall overnight with Valdez receiving about half of that.  Winds were moderate to strong out of the southeast that eventually shifted to southwest.  In addition to snow and wind, temperatures were rising overnight creating upside down storm slabs.  The avalanche hazard will be elevated today as the snowpack adjusts to this new load.  Human triggered avalanches up to 3 feet in depth are likely today.

    Instabilities are expected to exist within the new storm slabs in terrain steeper than 32°.  Areas where the new snow has been loaded deeper by south winds overnight will be the most sensitive.  

    Conservative terrain choices are reccomended today as the snowpack adjusts to its new load.  Use small inconsequential test slopes and hand pits to identify potential weakness within the new snow or at the interface.  Realize that new snow sensitivity will likely be higher on the lee side of terrain features, high elevation ridges and cross loaded terrain.  Watch for signs of instability including shooting cracks, collapsing and recent avalanche activity.  These are all a clear indication of unstable snow.

    Light to moderate snowfall today along with moderate southerly winds will continue to add weight and stress to new storm slabs.

     

  • Deep Persistent Slabs

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

    Heavy snowfall overnight has added stress to a potential weak layer that may exist in the continental zone and the northern portion of the intermountain .  The Thanksgiving rain crust was found to be facting and losing strength prior to the 12/11 storm below 4000' in the above mentioned area.  This layer may have been the weak layer responsible for some of the recent natural avalanche activity.

    It is unclear at this point if this layer is still 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

Heavy snowfall overnight has created elevated avalanche concerns today.  Storm slabs are upside down with deeper pockets of wind loaded snow on lee slopes that are expected to be reactive to human triggers up to 3 feet in depth.  Light to moderate snowfall and wind are forecasted to continue today.

There is a significant amount of snow available for transport.  This will allow for wind slabs to easily form where wind redistribution is occuring.  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.

 

Regions covered