Boletín de aludes

Continental

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.

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A variety of avalanche problems are expected today, creating a Considerable avalanche hazard. In upper elevations, triggering a storm slab up to 2 feet deep may be possible. Persistent weak layers found in specific mid-elevation areas will also create the possibility of 2-foot-deep avalanches. Additionally, above-freezing temperatures with rain and snow in lower elevations will likely produce wet, loose avalanches.  Pay attention to what avalanche problem applies to your area of travel today. For more information see the full forecast. 

Problemas de aludes

  • Storm Slabs

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

    Over the last 24 hours, 4-6 inches of snow has fallen through Thompson Pass and upper elevations. Continued snowfall today will gradually increase storm slab depths and the likelihood of triggering an avalanche 1-2 feet deep. Moderate SE winds will be redistributing new snow into deeper more sensitive pockets on the leeward side of terrain features at upper elevations. 

    Northerly winds on Wednesday transported moderate to large amounts of storm snow in Thompson Pass. In specific areas, there will be recently formed wind slabs underneath the recent storm snow. Windslab formation was more spotty and limited to ridgetops in the maritime and continental zones. Increased loading of these 2-day-old wind slabs could create activity in upper elevations and wind-affected shoulders through Thompson Pass. 

    Triggering a small storm slab could result in a larger avalanche over 2 feet deep on a persistent weak layer or within an old wind slab today. 

    Example of identifying wind patterns and the wind's effect across terrain. 2/26

    Photo: Gareth Brown

  • 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, a layer of surface hoar from Valentine's Day as well as a decomposing rain crust from a bit earlier. The extent of both layers is limited to lower elevations. Below 1500 feet a rain crust buried 12-16 inches has shown reactivity in recent observations. Collapsing with propagation in multiple locations has been taking place on this layer within the last few days. Currently, we have not seen any avalanche activity on this layer but that is becoming increasingly possible with continuing snow/rain loads as well as further weakening of the old rain crust. Use caution today if you end up on steep low elevation terrain. The crust is easily identifiable as you dig down a couple of feet. 

    Buried surface hoar from 2/14 exists in specific areas from 1500 -2500 feet.  Burial depth in the maritime zone is 16-20 inches and a bit shallower moving inland. This layer showed reactivity in pit tests earlier this week with clean shears in ECT tests. So far we are not seeing propagation or avalanche activity on this layer but that may change with continued stress.  

    We have a bit bit of uncertainty on the future reactivity of these two layers. For the time being, we are eying them with suspicion while expecting current weather conditions will continue to stress these layers. 

     

    (2/28/2025)

    Failure of the buried surface hoar on  a shear planar surface in pits tests. 

    Photo: Joshua McDonald

  • Loose Wet

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

    Above-freezing temperatures with rain/wet snow have been occurring from sea level to 1500 feet for over 24 hours creating the possibility for wet loose avalanches. The surface snow has already encountered above freezing temperatures which will dull the reaction the surface snow has today.  In areas where the upper snowpack becomes saturated a moderate amount of wet loose activity can be expected.

    When assessing wet loose hazards, it is essential to take the hazard in relation to the terrain you are exposing yourself to.  Are there terrain traps? Are there consequences if I were to be swept off my feet by even a small avalanche? 

    The size and shape of the terrain above you along with the amount of loose snow available to slide, directly correlates to the size of the wet loose activity that can occur. Terrain traps and exposure below you compound consequences.

     

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

Dry loose D1-2 natural activity releasing from steep terrain in the Port of Valdez and Thompson Pass

Forecast Discussion:

The gradual accumulation of storm snow is adding to the stress on weak layers in our snowpack. Today we expect there to be a possibility of triggering small storm slab avalanches. These could potentially step down into old layers of windslab in upper elevations today.  Areas, where stiffened storm snow, overlies windslab may be likely to produce an avalanche 2 feet deep. 

Persistent weak layers have shown signs of instability in specific low-mid elevation terrain. These layers have not yet produced avalanches but the likelihood of doing so is increasing. This is not a widespread problem but could take a traveler by surprise in isolated steep, low-elevation terrain. Use caution when traveling up or down through areas that may have persistent weak layers. Uncertainty exists on the future reactivity of these layers so we will be keeping a close watch and posting updates when we get more information. 

 

 

Additional Information:

Active rockfall has been recently reported in Keystone Canyon.

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- 2/27 24 hour Snow Water Equivalent Inches Height of Snow February Snowfall Inches Season Total Snowfall Valdez   0    0    50     10      Thompson Pass    2    N/O   N/O    N/O    ~500 Nicks    0    0    138    ~18 N/O 46 Mile    Trace     0   22    ~4 N/O

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