Boletín de aludes

Maritime

Valdez Avalanche Center
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Peligro de aludes

Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche hazard is Considerable above 1500' and moderate below.  Human triggered avalanches are likely up to 1 foot in depth.  Natural avalanches are possible.

Avalanche Forecasts are issued Wednesday-Sunday at 8am

Problemas de aludes

  • Storm Slabs

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

    New snowfall over the last 24 hours has increased the avalanche hazard.  Human triggered avalanches are likely today involving the new snow.  Snowfall totals of 11 inches were recorded at Sugarloaf snotel @ 500' near the coast and 5 inches  at the Tsaina and Nicks snotel.  Snowfall totals are unknown at upper elevations but are estimated at 12-18 inches in the Maritime zone and 8-12 inches for Thompson Pass and North.  

    Expect instabilities to exist at the interface of this new snow as bonding is a process that takes time and does not happen all at once.  Human triggered avalanches are most likely within 24 hours of a snowfall event, which is the time frame we are currently in.  South aspects and low elevations previously had a melt-freeze crust that may take longer for bonding to occur.   There is a low probability that avalanches could be triggered at layers deeper in the snowpack on isolated terrain features below 3000' (see problem 2).

    Pay attention to how much new snow has accumulated and how much wind redistribution has occurred.  Small inconsequential test slopes and hand shear pits are helpful tools for quickly gathering information on how well new snow has bonded.  Watch for signs of instability, such as shooting cracks, collapsing, and recent avalanche activity, indicating the snowpack has the energy required to produce an avalanche.

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2

    There are currently 2 persistent weak layers on our radar, both are believed to be limited to terrain below 3000'.    There is a layer of buried surface hoar from Valentine's Day as well as weak snow below a decomposing rain crust from late January.  We have not yet seen any avalanche activity on either of these layers, however new snowfall has added stress over the last 24 hours that may make these potential weak layers reactive to human triggers.

     Buried surface hoar from 2/14 exists in previously wind protected areas from 1500 -2500 feet.  This layer is difficult to identify as it has only been found in a narrow elevation band and exists in terrain that was protected from the strong outflow (North) wind event that occurred in late January.  This layer has been found on average between 12-20 inches in depth.

    Below 1500 feet, a rain crust is buried 16-20 inches, and has shown propagation beneath the crust in snow pits as recently as 3/5.  Due to the limited extent of elevation, this layer is only a concern in a limited amount of terrain.  This layer could be a concern in steep low elevation canyons, or on steep unsupported slopes below 1500'.  

      To limit exposure to both of these layers avoid terrain traps and consider using conservative terrain while moving through low elevations..  There is uncertainty on the current and future reactivity of these two layers. We are keeping these on our list, as current weather conditions will continue to stress these layers. 

     

    (3/3/2025)

    Developed surface hoar grain that has been found in a narrow elevation band in areas previously wind protected.  Cracked Ice/2000'/N/down 30cms

    Photo: Gareth Brown

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

  Small to moderate wet loose activity in steep low elevation terrain and south aspecxt up to 4000'

Forecast Discussion:

We have just received 6-12+ inches of new snow that will need time to bond with the snowpack.  Expect instabilities to exist today with convex terrain and wind loaded slopes being the most sensitve.  Prior to this snow a stable snowpack was in place above 3000' with good structure and strength.   The depth of instabilities is expected to be equal to the depth of new snow.  On solar aspects where a melt freeze crust previously existed at the surface, bonding may take longer.

Below 3000' the structure of the snowpack is not nearly as strong as mid-upper elevations, especially below 1500'.  Various rain crusts are in varying states of decay and weak snow has been observed below the uppermost crust.  This weakness in the snowpack is only expected to be a concern in steep low elevation terrain, but may be a concern for Ice Climbers trying to navigate steep unsupported slopes.

Buried surface hoar has been identified in a few places between 1500-2500'.  This layer has not shown signs of being reactive yet and the narrow elevation band is not conducive for significant human triggered avalanche propagations.  Although, small avalanches could be possible on isolated terrain features in terrain that is protected from outflow wind events below 2500'.  Incremental snowfall will continue to stress these layers where they exist.

 

Additional Information:

A weather and snowpack season history is available by clicking on the Season Summary tab which is located below the bottom line statement once you have entered the full forecast.

Season Snowfall Data

Location 24 hour Snowfall Inches- 3/2 24 hour Snow Water Equivalent Inches Height of Snow March Snowfall Inches Season Total Snowfall Valdez    3    .77    44     3 N/O     Thompson Pass    6    N/O   N/O     6    ~500 Nicks    5    N/O    143    5 N/O 46 Mile    4     .4   22    4 N/O

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