Avalanche forecast

Maritime

Valdez Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
No rating
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Out of date — this forecast expired 8 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche hazard has risen to Considerable.  Triggering an avalanche 1-2 feet in depth will be likely in areas where strong winds are forming new wind slabs. Watch for signs of new wind slab formation such fresh windlips, flagging, and pillowed snow surfaces.  Shooting cracks will be an indicator that new wind slabs are reactive.  Natural avalanches will be possible today.

There is no rating for low elevation in the Maritime zone due to a lack of snow.

Avalanche Forecasts will be issued 3 days/week during December.  The next forecast will be issued on Friday, December 12th.  5-day/week forecasts will return in January once 2026 funding comes through.

Avalanche problems

  • Wind Slabs

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

    Field observations over the last couple of days have found a variety of surface conditions, including an unexpected amount of soft snow.  We have decided to increase the hazard rating to Considerable due to the increase in North wind and the potential for new wind slabs to form.  It is unclear as to whether today's wind will redistribute the soft snow that has been observed, but it is our concern, especially if today's wind comes in at a slightly different direction to last weeks hurricane force event.

    Sensitive wind slabs are not expected to be widespread, expect stability to be variable.  Evaluating the hazard will require paying attention to the age of wind slabs.  The harder the wind slab is, the older it is and less likely for a person to trigger.  Newer slabs will be softer (4 finger-1 finger) and actively forming today.  Be dilligent with route finding and pay attention to wind loading patterns and changes in the surface snow.

    Avoid terrain traps and travel in gullies.  Shooting cracks will be a sign of instability that indicates you are on unstable snow and should avoid slopes steeper than 30°.

    Below 3000 feet a rain crust that formed on 12/1 may prevent the wind from eroding the snowpack below that level.  This rain crust will act as a smooth sliding surface on lee slopes where new wind slabs are formed.

     

  • Persistent Slabs

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

    Our early-season snowpack has shown a couple of weak layers of facets in the bottom 1/3 of our snowpack.  These layers have not been reactive in stability tests lately, but poor structure and facets are apparent.  It is expected that large natural avalanches on Tones Temple, Saphire, and Girls involved one of these faceted layers due to their wide connected propagations.  If this is correct, it shows that these layers can produce large avalanches when overloaded.  In this case it was the additional weight of wind slab formation on 12/5.  These layers will be under increased stress where new windslab formation is occurring.

    More information needs to be gathered about weak snow at the bottom of the snowpack.  But what we can understand is that facets exist in the lower snowpack, and they are growing everyday this cold arctic weather remains.   This weak snow may be difficult for a person or machine to directly overload, however thinner areas of the snowpack could be trigger points, and smaller wind slab avalanches have the potential of overloading facets, creating larger step down avalanches.

     

     

     

Avalanche Discussion

Avalanche activity in the last 72 hours:  Nothing in this time frame, but numerous natural slab avalanches from 12/5.

Forecast Discussion:  

Last weeks hurricane force North winds have done a lot of damage to our snowpack, with a significant decrease in mass.  The damage will continue today with gusts in the 80's expected on Thompson Pass.

There is currently a wide range of snow conditions in our forecast zone, all of which vary depending on the amount of wind exposure.  There is a rain crust up to ~3000, wind slabs that range from old and rock hard to soft slabs that will be forming today, soft old snow, sastrugi, and windward faceted slopes stripped nearly to the ground.  The avalanche hazard has been elevated due to the possibility of new wind slab formation.  

Evaluating snowpack stability today will require being attentive to changes in the surface snow.  It is expected that sensitivity of the snow will be variable ranging from harder, older wind slabs that are  unreactive to triggers, to fresh wind slabs that are ready to fail.  The depth of new slabs is expected to be 1 foot or less in depth but deeper pockets up to 2 feet may form in isolated areas.

Faceted snow in the bottom 1/3rd of the snowpack is not expected to be reactive today, but there is a chance that a smaller wind slab avalanche could overload this weak snow and create larger avalanches.  Current weather conditions will promote faceting and weakening of the  lower snowpack.

 

Additional Details:  There is no field data from the Maritime zone due to low snow coverage and thick brush restricting access.  Numerous Glide avalanches have released in the Maritime zone in the mid elevation band.  Some of these may have failed without previous visible glide cracks.  Avoid travel below glide cracks as they can fail at any time.  Their likelihood of failure is independent of the snowpack stability.  Check out the season summary tab for more information on the development of the snowpack.

 

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