Avalanche forecast

Continental

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. Shallow storm slabs less than 1 foot in depth have formed over the last two days that will be possible for a person to trigger in specific locations.  The hazard below 3000 feet will begin as low and move to moderate as the sun warms the surface of the snow and creates the potential for natural and human triggered wet loose avalanches.

 

Avalanche problems

  • Storm Slabs

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

    Shallow storm slabs have formed over the last couple of days above 3000'.  Below 3000' temperatures were above freezing with light rain occurring.  Snowfall reports ranged from a trace at Crudbusters, 2-4 inches in the Small Creek area, and 8 inches at 5000' on Loveland Basin.  This general trend shows more new snow towards the coast and less to the North.  Shallow human triggered avalanches will be possible today on specific terrain features such as convex slopes or unsupported terrain.  Winds were light over the last two days on all weather stations so deeper wind loaded pockets of snow are not expected to be widespread, however, these may exist in isolated locations at upper elevations and would have higher sensitivity where they exist.

    Near surface facets (weak snow) were observed on shaded aspects above 3000' before the storm that may act as a weak layer in areas that received greater than 6 inches of new snow.  Pay attention to new snowfall amounts and cohesion as these will be the greatest determining factors for stability today.  Hand pits and test slopes will be effective tools today in determining the sensitivity of the new snow.

    There is a small chance that shallow storm slab avalanches could step down to a layer of buried surface hoar ~ 2 feet deep in isolated shaded terrain above 3000' in the Continental zone.

  • Loose Wet

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

    New snowfall above 3000' will increase the likelihood and extent of wet loose activity today on steep rocky solar aspects at upper elevations.  Areas with the highest storm totals are expected to have the most activity.  Below 3000' wet loose activity is possible as well but the size is expected to be lower due to a rain crust that formed overnight that will take longer for the sun to break down and effect.  However, expect a wider range of aspects to be affected at low elevations.

    Wet loose avalanches offer clear instability indicators and are highly dependent on slope aspect. Monitor the sun's impact on the snow surface closely. Wet loose conditions become a concern when over 4 inches of snow becomes moist, particularly on steep, rocky slopes. The avalanche hazard does not affect all aspects simultaneously but  starts on east-facing slopes, shifting to south and then west. Stay vigilant to which slopes are most affected by solar heating and to what extent.

     

     

     

     

Avalanche Discussion

RECENT AVALANCHE ACTIVITY:  

Small to medium sized wet loose activity was observed over the last 48 hours.

DISCUSSION:

Shallow new snow instabilities are possible today.  The likelihood of human triggered avalanches will greatly depend upon new snowfall amounts and the amount of cohesion that new snow has.  Keep in mind that the cohesion of the new snow may increase during the day as the sun warms the snow surface, which will increase sensitivity.  Before the recent light round of snowfall stable conditions existed with a fair amount of near surface facets observed at the surface on shaded aspects above 3000'.  These facets that are now buried by new snowfall are not expected to be reactive in the majority of locations today due to insufficient storm slab depths and light winds.  

Snowpack assessment should be fairly straightforward today.  Pay attention to new snowfall amounts and how well it is bonded with the underlying snowpack.  The higher the new snowfall amounts are the higher the likelihood will be for a person or machine to trigger an avalanche.  New snow amounts will likely widely vary across our diverse forecast area, but are expected to be higher near the coast.  Hand pits and test slopes can be effective tools for judging stability.  Watch for the typical Spring hazards such as wet loose avalanches and overhanging cornices.

A layer of buried surface hoar that is 1-3' deep has been removed from our problem list as it became unreactive to human triggers last week and is isolated in its distribution.  There is a small chance that cornice fall or small storm slab avalanches could step down to this layer in isolated locations on northerly aspects above 3000' in the Continental zone.

A very significant Glide avalanche/ landslide in Upper Stuart Creek last week is a great reminder of the destructive forces involved with glide crack failure.  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: 269  inches

Valdez March snowfall: 20 inches

Valdez height of snowpack: 70 inches

Thompson Pass season snowfall: 596 inches as of 3/1

46 mile height of snowpack: 68 inches

 

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