Boletín de aludes

Continental

Valdez Avalanche Center
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Peligro de aludes

Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche hazard is Moderate above 2000 feet and low below.  Human triggered avalanches up to 1 foot in depth are possible in specific areas.  This would include places where wind slabs that were created on 1/9 exist.  Natural avalanches are unlikely.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    It has been 48 hours since the last north wind.  Wind slabs have become stiff and in a normal scenario would be stubborn to triggers moving towards unreactive.  Wind slabs that were created on 1/9 were deposited on faceted (weak) snow in most locations.  This weak snow will slow the healing process of wind slabs, which will likely be stubborn to triggers today but will remain possible up to 1 foot in depth.

    This type of problem may allow a person well onto the slope before it fails.  The stiffness of the current slab combined with the weak layer may allow failure to occur behind you on a slope .  Avoid traveling above terrain traps and exposure where old wind slabs are present.

    Check for the presence of wind loaded snow in the area you choose to travel.  The effectiveness of small test slopes will be decreasing as small slopes will likely now have good support and lower sensitivity.   Checking for the presence of facets beneath slabs is recommended.   

    The hazard will be lower in areas protected from the latest moderate outflow event.  Seek out sheltered snow for better riding quality and stabiity.  Light snowfall and light winds that are forecasted today are not expected to be substantial enough to negatively effect stability.

    Test slope failure at Benzene Alley on 1/9.

    Photo: Gareth Brown

  • Glide Cracks

    • Todas las altitudes
    Probabilidad
    Unlikely
    Tamaño
    2.5–3

     Glide avalanches are a strange beast that act differntly than other avalanche problems.  Full depth failure can occur 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

The main avalanche concern remains slopes loaded by recent wind.  Keeep in mind that facets formed during the last 2 weeks of mostly clear and cold weather may allow for instabilities to persist longer than what is typical.   

Good stability has been reported and observed in areas unaffected by recent wind.  The 1/7 snowfall was light for the Intermountain and continental zone with 2-6 inches observed.  The facets mentioned above have recently been buried by new snow, although a sufficient slab has not yet developed above this weak layer in areas unaffected by wind.  The Maritime zone received higher snowfall amounts (~8-10")  although this snow was quite dry and only involved .5 inches of water at sea level, which is still not enough to overwhelm this weak layer without the additional weight and cohesion of wind redistribution.

Light snowfall is in our forecast which will slowly add stress to the 1/7 buried surface hoar.  It is possible this layer will become a problem in the future.

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

Valdez season snowfall: 160 inches

Valdez January snowfall: 15 inches

Valdez height of snowpack: 62 inches

Thompson Pass snowfall data is currently unavalable

46 mile height of snowpack: 65 inches

Regiones cubiertas