Avalanche forecast

Continental

Valdez Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

The avalanche hazard will begin as low today on all aspects and elevations.  As the sun begins to melt the surface of the snow the hazard will increase to Considerable.  Human triggered and natural wet loose avalanches will become likely during the heat of the day.

This is the final week of public avalanche forecasts.  The last forecast of the season will be issued on Sunday 4/28.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    Wet loose avalanches are once again today's primary avalanche concern.   Another warm sunny day will occur today coupled with a light overnight freeze.  This will allow for hard frozen snow to become wet on aspects that are receiving direct sun.  Steep slopes with wet snow at the surface will be capable of producing wet loose avalanches.  Avoid travelling on or spending time below steep terrain where more than 4 inches of the surface snow is wet.

     This type of avalanche starts small and slow but can quickly grow and become dangerous, potentially burying or sweeping a person away, especially in steep, rocky areas or near cliffs.

    Today’s avalanche risk starts low in the morning and increases with the sun's warmth, first on east-facing slopes and later moving to south and west-northwest aspects as the day progresses. A slope that is frozen and stable in the morning might not be safe in the afternoon. Stay off steep slopes that catch the sun during warm periods.

    To stay safe, be mindful of the sun's path and avoid steep sunny slopes during their warmest times. Always consider the terrain below you, avoiding areas that could amplify the consequences of an avalanche, like cliffs and gullies.

    (4/25/2024)

    Natural wet loose and wet slab avalanches on South Three Pigs

    Photo: Gareth Brown

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    The degree of natural avalanche activity is increasing with each sunny day.  Several large natural wet slab releases have been noted over the last few days on steep south faces.  Light overnight freezes have been sufficient to refreeze the surface snow each day, however, daytime heat is slowly penetrating deeper into the snowpack with each diurnal cycle.  As this process continues wet slabs are expected to continue to release on steep south aspects and may begin to happen on other aspects as well.

    There is still a lot of snow mass in the mountains.  Daytime high and low temperatures have increased significantly over the last week.  This change puts stress on the snowpack.  The first signs of stress are in the form of wet loose activity that occurs at the surface.  As heat can penetrate deeper into the snowpack it becomes more likely for stress to be relieved in the form of wet slabs as old interfaces deeper in the snowpack that were dormant become lubricated by meltwater and reactivate.  Identifying which slopes are prone to this kind of release is difficult.  What we can do is recognize that this type of activity will be most likely to occur during the heat of the day when more than 6 inches of the surface is wet and the snowpack begins to be unsupportable on foot.  Avoid steep terrain when these conditions are present.

    (4/24/2024)

    Wet slab release near the toe of the Worthington Glacier

    Photo: Gareth Brown

Avalanche Discussion

RECENT AVALANCHE ACTIVITY:  

Last 48 hours: Large Wet loose and wet slab natural avalanche activity has been on steep south facing terrain, with notable activity on Three Pigs. 

DISCUSSION:

2 weeks of dry and sunny weather have allowed our snowpack to transition to spring conditions with diurnal swings in the hazard level dictated by solar input.  Snowpack stability will vary significantly depending on the time of day and aspect.  In areas where the snow surface is frozen, the hazard is low.  As the sun warms and melts the surface the hazard will increase to moderate and then Considerable depending upon the depth of wet snow that exists.

 The daily swing in avalanche hazard is currently very predictable making mitigation of this hazard far more straightforward than avoiding other avalanche problems.  The main hazard for users will be exposing themselves to steep terrain that is baking in the sun.  Keep in mind that triggering wet loose activity is not the only concern, but includes staying out of the way of the natural shedding process that occurs each day.  Avoid grouping up and spending time beneath large sunny slopes especially ones with cornices.

Wet slab activity is becoming more likely during the heat of the day as heat is beginning to penetrate deeper into the snowpack.  Wet slab releases involve far more mass than a typical wet loose release making them far more dangerous.

Additional Concerns:

This is the time of year when cornices begin to fail.  You can significantly reduce your overall exposure in the mountains this time of year by avoiding traveling on top of or under cornices.

Glide crack releases have been observed on the southern aspects of Town Mountain lately.  Glide cracks exist in isolated areas and will be a hazard throughout the season until they fail.  Avoid exposure to glide cracks.

Valdez season snowfall: 286  inches

Valdez April snowfall: 11 inches

Valdez height of snowpack: 59 inches

Thompson Pass season snowfall: 698 inches as of 4/5

46 mile height of snowpack: 52 inches

 

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