Bulletin d’avalanche

Continental

Valdez Avalanche Center
Voir sur la carte

Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 8 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche hazard is moderate.  It will be possible to trigger an avalanche 1-2 feet deep on a recently wind loaded slope.  Natural avalanches are unlikely 

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.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Winds have subsided overnight, but remain strong.  Wind slabs that formed yesterday will be less sensitive today.  If you decide to travel in avalanche terrain today, keep an eye out for wind slabs that were recently formed.  These will be the areas that are possible for a person or machine to trigger an avalanche.  Newer wind slabs will be softer than slabs that formed a week ago.  You can differentiate a wind slabs age by a simple hand hardness test.  If you are unable to penetrate the slab with one finger using a fair amount of pressure, it is older and unlikely to trigger.   Softer slabs will be more likely to  remain reactive.

    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

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    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 has occurred.

    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:  

A prolonged period of strong winds has significantly eroded our snowpack.

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 formed yesterday, soft old snow, sastrugi, and windward faceted slopes stripped nearly to the ground.  

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 more sensitive.  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.

 

Régions couvertes