Bollettino valanghe

Maritime

Valdez Avalanche Center
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In sintesi

The avalanche hazard is Considerable at all elevations.  Heavy snowfall overnight will continue through the day today, making human triggered avalanches likely 1-3 feet in depth.  Natural avalanches are possible.

Avalanche forecasts are issued Wednesday through Sunday.  The next avalanche forecast will be available on 12/18.

Problemi valanghivi

  • Storm Slabs

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

    Moderate-Heavy snowfall began during the day on Saturday and is expected to continue through tonight.  Sugar snotel in Valdez reported 5" of snow at 5:30 am and Thompson Pass wx station reported 14".  An additional 12-18" of new snow is possible by Monday morning at upper elevations.  Winds have been light-moderate, but are still sufficient enough to redistribute the new dry snow into deeper pockets that would be more sensitive to human triggers.  

    Expect to find storm slabs around 1 foot in depth today at upper elevations with wind loaded drifts up to 3 feet in depth possible in cross loaded gullies and near high elevation ridges.  Winds on Thompson Pass switched from south to north Saturday evening, so expect various aspects to potentially be loaded.  Below 3000' this new snow is being deposited on a stout rain crust from 12/11.  New snowfall amounts may be lower at low elevation, but poor bonding of new snow on the rain crust was observed on 12/14.  At low elevation use caution in areas where steep brush free terrain exists.  At mid and upper elevations pay attention to the amount of new snow that has fallen, the amount of wind loading that has occurred and watch for red flags such as shooting cracks, collapsing and recent avalanche activity that indicate the snowpack is under stress.  

    Even if red flags are not present realize that when snow rapidly accumulates as it is now, the avalanche hazard will rapidly increase during and directly after a snowfall event.  If you travel in the backcountry today, conservative terrain choices and cautious route finding are recommended.

    (12/15/2024) Photo: NWS

Avalanche Discussion

Want to learn more? Check out our new Weather History tab.  You can find this when you open up the full forecast.

Avalanche Activity last 72 hours: None observed

Heavy new snowfall overnight is forming fresh storm slabs that are expected to be sensitive to human triggers today.  This new snow is falling on a variety of snow surfaces including rain crust below 3500'.  Above 3500'  there are several layers in the upper snowpack that have the possibility of acting as a weak layer or bed surface.  There is a rain crust from 12/5 about a foot beneath the current new/old interface that extends up to 4500' in some places.  This layer has been observed to be breaking down and has the potential to act as a weak layer.  This layer has not been producing results in stability tests so far, but is worth watching as additional snowfall applies further stress. 

Below this rain crust another 6-8 inches depending upon wind redistribution and location is the November wind board.  This layer has been showing good bonding, but could act as an effective bed surface if the snow above it becomes overloaded.  In some places this layer of windboard has been observed to be breaking down and losing strength, facets exist beneath this layer.  

This may sound like an overload of information, but what you can take out of it is that the upper snowpack is still highly variable and has been undergoing a lot of change recently with decent sized storms moving through and warm temperatures reaching into upper elevations.  As these changes are taking place it is possible that layers in the snowpack to become reactive as the snow load and stress increases.  There have been very few public observations this season along with long periods of stormy weather preventing travel to upper elevations.  Conditions may vary from the information that is provided here.  Individual snowpack evaluation is important if you decide to travel in avalanche terrain.

If you travel in the Continental zone today, exercise extra caution as there is very limited field data from this location.  It is unclear as to whether deep slab instabilities exist, however it is a possibility.

If you get out in the mountains today consider leaving an observation to help increase the understanding of current snowpack stability.

Season Snowfall Data

Location 24 hour Snowfall Inches- 12/15 24 hour Snow Water Equivalent Inches Height of Snow December Snowfall Season Total Snowfall Valdez    5 N/O       Thompson Pass    14 N/O N/O    25    141 Nicks    5 N/O    41    22 N/O 46 Mile    1   N/O   14    4 N/O

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