Bollettino valanghe

Continental

Valdez Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

 Considerable avalanche hazard above 1500 feet is expected NE winds. will be actively creating wind slabs in exposed terrain. It will be possible for backcountry users to trigger an avalanche 1-2 feet deep on recently wind-deposited snow.  Smaller avalanches within unconsolidated storm snow are also possible. 

Avalanche Forecasts are issued Wednesday-Sunday at 8am

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Recent snow from Wed/Thurs deposited 11 inches at Sugarloaf snotel @ 500' near the coast and 5 inches at the Tsaina and Nicks snotel.  Observations from yesterday confirmed these amounts at low and mid-elevations. 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.  

    Moderate and isolated strong NE winds will redeposit recent storm snow into fresh wind slabs that could be triggered by a human today. The forecast is calling for a short-lived wind event that should taper off by tonight or tomorrow. In the meantime, areas near Thompson Pass Summit and high elevations in Port Valdez will see active wind transport and deposition with an increasing avalanche hazard throughout the day. If you travel in windy areas today it will be possible to trigger a windslab 1-2 feet deep.  Areas that remain unaffected by the wind will have softer unconsolidated storm snow up to 1 foot deep. Instability within this snow and at the interfaces below could produce small soft slabs in isolated areas today. 

     Stiffer wind-affected snow may produce shooting cracks or collapses indicating the snowpack has the energy required to produce an avalanche.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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.  Yesterday an additional foot of wet snow increased stress on these layers but no associated avalanche activity was observed. 

     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 low elevation, this 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'.  Use caution when traveling through low elevations with poor snowpack structure. 

     To limit exposure to both of these layers avoid terrain traps and consider using conservative terrain while moving through low elevations..  There is uncertainty about 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 aspects up to 4000'

Forecast Discussion:

For the last month or so we have been finding a strong snowpack with good structure above 2000 feet. Instabilities that we have been monitoring are mostly found in the top 2 feet of the snowpack. Consistent light to moderate snowfall has been building storm slabs on the surface with short-term instabilities immediately after storms. Wind slabs that form today will increase the depth and sensitivity of our upper snowpack making human-triggered avalanches 1-2 feet deep likely in specific areas.

Below 2000' 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. We have not seen any significant avalanche activity on these layers but pit tests show moderate reactivity in specific areas. 

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.  However, 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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