Avalanche forecast

Maritime

Valdez Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The avalanche hazard is Moderate at all elevations. Human triggered avalanches will be possible today up to one foot in depth in wind affected areas.  Natural wet loose avalanches at low elevation are possible in steep terrrain.

Public avalanche forecasts are issued Wednesday- Sunday at 8 am

Avalanche problems

  • Loose Wet

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

    Wet loose activity was low to moderate yesterday as temperatures climbed above the freezing mark once again during the day at low elevations.  The February sun has some power now, and yesterday, rollerballs were observed releasing from rocks on South aspects of Moonlight Basin into the mid elevation band.  This low to moderate wet loose activity is expected to continue today as observations from Keystone Canyon yesterday showed only a very thin melt freeze crust at the surface with ~6 inches of dry snow beneath.  If this crust is able to break down during the heat of the day, dry snow will become susceptible to wet loose activity.  Wet loose activity is expected to be confined to the 6-10" of settled new snow that has fallen over the last week.  

    Today, wet loose activity will largely depend on if and how much the sun can pop out of the clouds, and is expected to be more aspect dependent than it was a couple days ago when temperatures reached a short term peak and all aspects were active.  Pay attention to the effect the sun is having on the surface snow in the area you choose to travel.

     When assessing wet loose hazard, 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.

  • Wind Slabs

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

    Observations over the last week have shown 6-10 inches of settled new snow since 2/14 that has become well bonded and has minimal wind affect in the majority of areas.  This snow did not come all at once but rather in a few small pulses, allowing the snowpack to adjust to the new load.  A storm slab avalanche problem has been switched to wind slab today due to repeated observations of the new snow being well bonded without signs of instability in areas without wind effect.

    Small areas of instability have been noted where the new snow has been affected by wind.   There are likely slopes below high elevation ridges and in wind channeled terrain or cross-loaded gullies where there are wind loads of sufficient size for a person to trigger an avalanche up to 1 foot in depth in steep terrain.  Watch for signs of wind loaded snow such as fresh wind lips, and areas that have a pillowed look or rippled texture.  

    For better stability and riding quality, seek out areas that are unaffected by wind, luckily these areas are pretty easy to find right now.

     

    Signs of instability within a small pocket of wind loaded snow. Loveland Basin 2/19

    Photo: Gareth Brown

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

Numerous small wet loose slides at low elevation on the South side of Thompson Pass

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.

For a more detailed Keystone Canyon observation with full pit profile click link here.

Forecast Discussion:

Wet loose avalanches are a concern at low elevations in steep terrain.  This problem should be more aspect dependant today as we are now in more of a diurnal temperature swing rather than under the influence of a warm coastal air mass.

New snowfall amounts over the last week have been light and gradual with 6" settled down low and up to 10" up high.  This has not caused a dramatic increase in the avalanche hazard as storm slabs remain shallow and winds have been light.  This new snow is falling on buried surface hoar up to 3k, with very developed grains between 1500'- 2500' depending upon location.  Despite the weak snow at the interface at specific elevations, shallow slabs (~6") have not yet created an issue except for consequential low elevation terrain.  Above 3k the new snow is well bonded to old wind affected surfaces with a notable low amount of spatial variability.

At low elevations in Keystone canyon there ~6 inches of dry snow above a rain crust from late January. Below this crust is a layer of facted snow.  These facets showed signs of propagation in ECT tests when isolated.  This has not been listed as a specific avalanche problem as it is unlikely for a person to cause the rain crust to fail on a slope of any reasonable size due to its connective strength.   There is a concern though, that this layer could produce human triggered avalanches up to 1 foot in depth on steep unsupported slopes where the continuity of the rain crust could be compromised and act as a slab.

Consistent cloudiness with a couple breaks in the clouds and trace snowfall amounts are expected over the next few days.  

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.

 

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- 2/19 24 hour Snow Water Equivalent Inches Height of Snow February Snowfall Inches Season Total Snowfall Valdez   0    0    50     10      Thompson Pass    0    0   N/O    9    ~500 Nicks    0    0    143    6 N/O 46 Mile    0     0   24    4 N/O

Regions covered