Avalanche forecast

Maritime

Valdez Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche hazard is Considerable above 3000 feet and moderate below.  Over a foot of new snow is expected to exist at upper elevations of the Maritime climate zone.  Human triggered avalanches are likely 1-2 feet in depth at upper elevations. Natural avalanches are possible.

Public avalanche forecasts are issued Wednesday- Sunday at 8 am

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The primary avalanche hazard for the day will consist of the new snow that has fallen over the last 36 hours.   The hazard level will range from low to Considerable across our forecast area depending upon the amount of new snowfall that has accumulated and how much wind has been associated with the new snow.  Before this much needed refresh of snowfall, the snowpack was stable.  Today, we can concentrate our snowpack evaluation on the surface snow, how much is there, and what effect the wind has had on this new snow.  Even though new snowfall amounts will vary, we have not yet received enough snowfall to affect deeper layers in the snowpack anywhere in our forecast area.

    The range of hazard level can be thought about and assesed like this.  In areas where there is less than 8 inches of uncohesive snow the chance of triggering an avalanche remains low.  Without cohesion in the new snow there is no slab and human triggered avalanches remain unlikely.  With any input from wind the new snow will gain slab character and human triggered avalanches will become possible.  This describes a Moderate hazard level, and is where the hazard level has been posted for all areas but the upper elevation Maritime zone.  In areas where there is more than 12 inches of new snow human triggered avalanches will be possible even without wind effect on the snow, especially in convex terrain.  Once wind effect is added, human triggered avalanches are likely in areas that have received greater than 12 inches.  These conditions are expected to exist in the upper elevations of the Maritime zone.  Buried surface hoar exists below 3000 feet and will act as a potential weak layer in areas where a slab has formed.

    Pay attention to new snowfall amounts 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.  

     

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Although not currently a problem, wet loose avalanches will become likely if snow switches to rain.  This change is expected sometime on Sunday, but if the switch happens today, then expect for 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.  As described above, 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 tomorrow.  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- 2/15 24 hour Snow Water Equivalent Inches Height of Snow February Snowfall Inches Season Total Snowfall Valdez    6    N/O    30     10      Thompson Pass    5    N/O   N/O    9    ~500 Nicks    2    N/O    143    6 N/O 46 Mile    2     N/O   22    4 N/O

Regions covered