Avalanche forecast

Maritime

Valdez 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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche hazard is Moderate above 3000' and Low below.  In the last 24 hours our area received 1-2 inches of snow at mid and low elevation atop a slick bed surface.  New snow amounts are insufficient to elevate the hazard below 3000 feet, but will increase once heavy snow arrives that is forecasted for tonight.  Above 3000 feet new snow amounts are uncertain, shallow slabs may exist that will be possible to trigger less than 1 foot in depth.

The hazard will be higher at mid and low elevations if heavy snow arrives earlier than forecasted.

 

 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    The storm that was anticipated to begin last night affected areas to our east, with only minor accumulations in our forecast area (1-2 inches).  The avalanche hazard will be similar to yesterday.  Snowfall is beginning to accumulate on a slick bed surface, but is not yet enough to pose a concern (no slab).  The exception to this would be in extreme terrain above exposure where small sluffs could knock you off your feet.  As mentioned above new snow is falling on a slick bed surface and poor bonding is initially anticipated.  Once more than 4 inches of snow accumulates instabilities will be possible in specific areas where wind has formed sensitive deeper pockets.  Once more than 10 inches of snow has accumulated  the possibility for instabilities will become more widespread.

    Pay attention to new snow amounts and watch for areas where winds have formed deeper pockets that may be sensitive.  Watch for signs of instability such as shooting cracks.  Wind loaded areas will be concentrated to wind channeled terrain and high elevation ridges as winds are forecasted to be light, but are still strong in close proximity to  gaps and passes like Thompson Pass.

     

     

    Example of varied bed surface from 1/26. 1 inch of new snow atop small rough sastrugi in the foreground with smooth windboard in the backround.  All surfaces are pencil to knife hard below new snow.

    Photo: Gareth Brown

  • Glide Cracks

    • All elevations
    Likelihood
    Unlikely
    Size
    2.5–3

     Glide avalanches are a strange beast that act differntly than other avalanche problems.  Full depth failure occurs independent of snowpack stability.  Or in other words, they can release even when a stable snowpack is in place.

    Since it is not possible to time their sensitivity the only way to mitigate this hazard is by avoidance.  First identify where glide cracks exist and avoid spending time beneath them.  Glide cracks are easy to identify.  They look like crevasses, but exist in non glaciated terrain.

    These do not produce small avalanches,  but rather failure will include the entire snowpack.  

    Glide release on Town mountain

    Photo: Rich Lofton

Avalanche Discussion

Light snowfall yesterday and today is not expected to be sufficient to increase the avalanche hazard, except maybe at upper elevations where higher amounts are possible coupled with moderate winds.  

As heavy snowfall begins the hazard will rapidly increase.  On 1/26  old wind affected snow was found to be variable with 6-12 inch sastrugi in places creating a rough bed surface.  Other places very hard and smooth wind board was observed.  In these areas a low friction bed surface exists that new snow may have a hard time bonding to initially.  

As new snow accumulates we should assume that it will intially have a hard time sticking to the old snow until we prove differently.  Pay attention to new snow amounts and the amount of wind redistribution that is occuring.

Glide cracks have been observed in all three forecast zones.  Avoid travelling beneath these as full depth avalanches can release unexpectedly.

Valdez season snowfall: 171 inches

Valdez January snowfall: 27 inches

Valdez height of snowpack: 52 inches

Thompson Pass snowfall data is currently unavailable

46 mile height of snowpack: 66 inches

Regions covered