Bulletin d’avalanche

Maritime

Valdez Avalanche Center
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Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche hazard is Moderate at all elevations. Human triggered avalanches will be possible today 12-18 inches in depth.  Natural wet loose avalanches at low elevation will also become possible if snow switches to rain during the day.

Public avalanche forecasts are issued Wednesday- Sunday at 8 am

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    The primary avalanche hazard for the day will continue to revolve around the snow that has accumulated over the past couple of days.  The Maritime snow climate zone has received the higher amounts with 10-12 inches average at mid elevation while the Intermountain zone has 6-8 inches average new snow depth.  Multiple observations from yesterday found the snow to be uncohesive and showing signs of bonding to old wind affected surfaces.  We expect this new snow to become more cohesive "slabby" today as new snow settles with time along with a forecasted increase in temperatures.  As cohesion increases human triggered avalanches will be possible equal to the depth of the new snow.  Areas that have been stiifened additionally by wind will be the most sensitive areas.

    This new snow has been deposited on Surface Hoar below 3000,  due to the uncohesive nature of the new snow along with shallow depths we currently don't expect this layer to be widespread reactive , but with subsequent loading that is expected this week this layer should not be forgotten about as slab depths increase.  In areas below 3000' that have formed a slab buried surface hoar could act as a failure plane for shallow avalanches.

    Pay attention to new snowfall totals and the amount of wind that has been associated with the new snow.  Hand shear pits are a quick way to gather information on how well the new snow is bonding and how much cohesion there is. Keep in mind that an increase in cohesion can be subtle and can change over a short distance.  Watch for signs of instability such as shooting cracks, collapsing and natural avalanche activity.  The presence of any one of these  indicates the snow has the energy to produce an avalanche.

     

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Although not currently a problem, wet loose avalanches will become likely if snow switches to rain.  This change is expected sometime today.  If the switch does occur, expect wet loose to become a concern in steep low elevation terrain, as the dry snow will rapidly lose strength once it comes into contact with liquid precipitation.  A firm bed surface beneath the new snow will allow natural wet loose activity to run fast and long distances depending upon terrain shape.  Avoid terrain traps and large steep slopes at low elevation if snow turns to rain.

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

None

For information about the previous Deep slab avalanche cycle, click the avalanches tab below the bottom line statement once you have entered the full forecast for a partial documentation of activity.

Three Pigs natural avalanche information click link here.

Forecast Discussion:

We are at the beginning of a new stage in our snowpack.  Prior to this recent snowfall, 2 weeks of clear weather allowed the snowpack to become stable, showing good strength and structure in multiple locations, elevations and aspects. During this clear weather surface hoar formed below 3000'.  

New snowfall is just beginning to change the snowpack stability, but just at the surface so far.  This change is variable dependant upon location.  Some areas remain dust on crust with low hazard, while others are beginning to develop shallow slabs.  Storm slabs will be increasing in depth and distribution as time moves on if the extended weather forecast of continued snowfall proves true.  Pay attention to the development of slabs at the surface, and keep in mind that conditions will likely vary along with hazard level from place to place.  Buried surface hoar is expected to become more of a concern in the future as it is incrementally loaded and a slab continues to grow in depth and distribution.

Snowfall is forecasted to turn to rain along the coast today.  If this happens during the day, expect for wet loose conditions to become likely in steep low elevation terrain as the dry snow will rapidly lose strength once rain on snow occurs.

There has not been any natural or human-triggered avalanche activity since the beginning of the month.  The deep slab avalanches that occurred in late January are now believed to be a dormant problem that will require a significant change in weather to reactivate.

 

 

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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- 2/16 24 hour Snow Water Equivalent Inches Height of Snow February Snowfall Inches Season Total Snowfall Valdez    2    N/O    50     10      Thompson Pass    N/O    N/O   N/O    9    ~500 Nicks    1    N/O    143    6 N/O 46 Mile    Trace     N/O   24    4 N/O

Régions couvertes