Bollettino valanghe

Continental

Valdez Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

The avalanche hazard is moderate above 3000 feet  Human triggered avalanches may be possible 1-2 feet in depth in specific areas, including those where new snow has been loaded into deeper drifts by recent storm wind.  Below 3000 feet the hazard is low, a rain saturated snowpack has frozen and gained strength in these areas.  Natural avalanches are unlikely at all elevations.

 

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    The most recent storm is in the process of clearing out with snowfall totals that are variable due to wind loading patterns and elevation.  Below 3000' the avalanche hazard is low, there is only a trace of snow on top of a supportable rain crust.   This rain crust becomes very thin above 3000' and is difficult to detect by 4000'.  

    Above 3000' new snowfall totals slowly increase, with the depth variable due to wind distribution.  On 12/12 4-8 inches of storm snow existed on Catchers Mitt at 4000' with deeper pockets up to 2' in depth existing on the lee side of terrain features loaded by recent SE wind.  These deeper pockets of windloaded storm snow were reactive on test slopes indicating that human triggered avalanches could be possible up to 2' in depth in specific locations.  At upper elevations it is expected that storm snow totals will be greater and human triggered avalanches will be possible in steep terrain, even in areas that are not wind loaded.

    Pay attention to the depth of the new snow in the area you choose to travel and the previous wind loading patterns that are present.  Try to anticipate what slopes will be loaded and avoid these areas.  Using small inconsequential test slopes on loaded and non loaded slopes will help to gain an understanding of the sensitivity of the new snow in the area you choose to travel.  As always, watch for red flags such as recent avalanche activity, shooting cracks and collapsing that would indicate unstable snow.

    Sensitive pocket of wind loaded snow on the lee side of a terrain feature

    Photo: Gareth Brown

  • Glide Cracks

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    2–2.5

    Numerous Glide Cracks exist on the North facing Buttressess of Nicks through Cracked Ice between 2000'-3000'.  Identify where these are if you decide to travel in this area and avoid traveling on or below them.  Glide cracks act differently than all the other avalanche problems and can fail even when the general hazard is low and without signs of instability.  Stability of Glide cracks has more to do with the relationship with the friction at the ground and less so to do with the weather that is effecting the surface like other avalanche problems.  Little is known about assessing glide cracks, so travel advice is simple: Avoid them.

    Numerous Glide Cracks on the Cracked Ice Buttress

    Photo: Kyle Sobek

Avalanche Discussion

Want to learn more? Check out our new Weather History tab.  You can find this when you open up the full forecast.

Avalanche Activity last 72 hours: Numerous wet loose avalanches to size D2 on all aspects were observed in the Maritime climate zone in steep upper elevation terrain during a brief break in the clouds on 12/10.

No slab avalnche activity has been observed since the wind slab avalanche cycle of 11/19.

A high degree of uncertainty continues to exist in the upper snowpack regarding new snowfall amounts due to limited observations during the last 2 weeks of stormy weather.  

The most recent storm produced moderate amounts of rain up to 3000' with the freezing line rising well above that for a brief period.  the snowpack is rain saturated below 3k and is now refrozen and strong.  Above 3k new snowfall amounts are still pretty minimal below 4k but steadily increase in depth as the rain crust that formed 12/10-11 disappears with elevation.   At mid elevations instabilities are likely concentrated to wind loaded areas.  As elevation increases, instabilities are likely to be more widespread as new snowfall amounts increase.  Snowpack evaluation is recommended as stability will vary depending upon elevation and wind distribution of new snow.

Good bonding at the November wind damaged snow continues to be observed.  However, the layer of snow just above is still slightly upside down and the november wind damaged snow could act as an effective bed surface. Stability tests have not produced results at this layer recently but it is still worth watching in case this develops into a persistent weak layer as the slab above it grows with continued accumulating snowfall.  

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.

Season Snowfall Data

Location 24 hour Snowfall Inches- 12/7 24 hour Snow Water Equivalent Inches Height of Snow December Snowfall Season Total Snowfall Valdez    0 .13       Thompson Pass    3 N/O N/O    25    127 Nicks    2 N/O    41    22 N/O 46 Mile    0   0   14    3 N/O

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