Bollettino valanghe

Maritime

Valdez Avalanche Center
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In sintesi

The avalanche hazard is Moderate at all elevations.  Human triggered avalanches will be possible today up to 1 foot in depth. Areas where new snow has been drifted by southerly winds will be the most succeptible.  Natural avalanches are unlikely.

 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Shallow storm slabs have been forming since the 22nd, with snowfall amounts ranging from 4 inches at lower elevations to 12 inches above 3000'.  Valdez has received mostly rain during this time although the freezing line dropped overnight with the sugarloaf snotel picking up a couple inches at 500'.  This new snow has gradually accumulated which will allow the snowpack to accept this new weight without a sharp decrease in stability in most areas.  Places that are a concern today include wind loaded slopes near high elevation ridges, the lee side of terrain features and cross loaded terrain.  Moderate -light winds have been blowing from multiple directions over the last few days but have been primarily southerly. 

    Other areas that would be a concern would be mid and low elevations where this new snow has accumulated on top of surface hoar.  Surface hoar is a notoriously weak layer because it is strong in compression and weak in shear.  There are a couple of reasons why this weak layer is expected to be limited in its effect in our sitiuation.  The first is that formation of this layer was only observed at and below brushline.    secondly, most areas below brushline are still very thick with exposed alders, which will prevent continous slabs from building.  Areas at mid and low elevations on Thompson Pass could be a concern where steep open slopes exist.  Steep slopes just above brushline could be a concern as well.  Rain at low elevations of the Maritime zone have destroyed this layer.

    This layer was identified in the Cracked Ice zone but was absent near Thompson Pass on Little Oddessey and Loveland Basin where wind prior to the recent snowfall would have knocked it over before being buried.

    Pay attention to new snow depth and wind redistribution patterns.  Watch for signs of instability such as shooting cracks, collapsing and recent avalanche activity.  Hasty hand shear pits and small test slopes are a great way to quickly gather information about the stability of the upper snowpack in the area you choose to travel.

     

    (12/23/2024)

    small shooting cracks on 12/22 BSH. Cracked Ice 12/23 2500'

    Photo: Gareth Brown

Avalanche Discussion

Observed Avalanche Activity last 72 hours: 

NONE

Wet loose concerns at low elevations of the Maritime zone will come to an end as temperatures are falling and the freezing line is expected to return to sea level.  On Thompson Pass and north precipitation type remained all snow over the last few days.  Shallow storm slabs have formed that are 4-12 inches in depth with signs of instability present below brushline due to buried surface hoar.  This will be a hazard in isolated areas where steep open slopes exist at mid and lower elevations.  Steep terrain just above brushline could be a concern as well.  Most slopes in this elevation band have very thick vegetation that will prevent contionous slab formation and failure.  This layer has not been observed at upper elevations yet.  Be on the lookout for this layer and pay attention to signs of instability that could indicate it's presence.  More observations are necessary to determine wether this layer will become a persistent slab issue. 

Winds were light to moderate and mostly southerly during the last few days.  Watch for areas where the surface snow is stiffer at the surface, indicating wind redistribution.  Wind loaded pockets up to a foot in depth were observed in Loveland Basin on 12/24 on the lee side of terrain features.  It will be possible to encounter areas of unstable snow today where the new snow has been loaded deeper by recent wind.  

Continue to avoid Glide cracks in the area where they exist from Nick's Buttress through Cracked Ice at mid elevation.

If you travel in the Continental zone today, exercise extra caution as there is very limited field data from this location.  It is unclear as to whether deep slab instabilities exist, however it is a possibility.

If you get out in the mountains today consider leaving an observation to help increase the understanding of current snowpack stability.  

A weather and snowpack season history is available by clicking on the Weather History tab that is located above the bottom line statement once you have entered the full forecast.

Season Snowfall Data

Location 24 hour Snowfall Inches- 12/25 24 hour Snow Water Equivalent Inches Height of Snow December Snowfall Season Total Snowfall Valdez    0 N/O         27     35 Thompson Pass    1 N/O   N/O    N/O    N/O Nicks    1 N/O    44    24 N/O 46 Mile    0   N/O   20    8 N/O

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