Bulletin d’avalanche

Maritime

Valdez Avalanche Center
Voir sur la carte

Danger d’avalanche

Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
Open full map
Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The avalanche hazard is Considerable above 4000 feet, Moderate 1500-3000 feet and Low below 1500'.  New snowfall amounts are unknown at upper elevation, instabilities could exist within this new snow.  Wet loose avalanche hazard remains a concern between 1500-3000 feet, but is on the decrease as colder arrives today.

The hazard is low below 1500' due to insufficient amounts of snow coverage to produce avalanches.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5

    Rain continues to occur below 2000' with snow above as of 6am.  This overnight drop in temperatures should slowly end wet loose hazard above 2000' for the time being as a crust forms at the surface.  Below 2000', there is very little snow on the upstream end of Keystone Canyon which will limit the potential size of wet loose activity.  This snow has already been rain saturated, and with temperatures moving towards freezing north of Kestone Canyon wet loose hazard is expected to be on the decrease.

    Downstream of Keystone Canyon temperatures are still well above freezing. However, there is insufficient snow to make wet loose avalanches a concern at low elevations.  

    Triggering a wet loose slide is still a possibility today, but the areas of concern will become more specific.  Steep slopes above terrain traps like canyons or gullies should be considered hazardous.  Also steep slopes that are free from brush should be approached carefully.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2.5

    Snowfall has been occurring at upper elevation for the last 72+ hours at a fairly steady pace.  New snowfall amounts are unclear, but it can be assumed there is 1-2+ feet of new snow that has fallen above 5000'.    4-6 inches of additional snowfall is expected today above 2000', along with light winds, which will continue to add stress to new storm slabs.  Human triggered avalanches are likely at upper elevations where the deepest storm slabs exist.  Southeast winds have been moderate to strong through most of the storm, creating deeper pockets of storm snow in specific locations.

    As you move down in elevation storm totals will be lower as above freezing temperatures on 12/10-11 have limited accumulations.  During the evening/night of 12/10, the freezing line likely climbed to 5000' for a period.   Pay attention to the depth of new snow in the area you choose to travel.  New snowfall depths will coincide with the likelihood of triggering an avalanche.  Along with the depth of new snow, also pay attention to how recent storm wind has redistributed the snow.  Use small inconsequential test slopes and hand pits to gather information about stability.  Watch for red flags such as recent avalanche activity, shooting cracks, and collapsing.  If any of these are present, it is recommended to stick to lower angle terrain.

    Photo: Gareth Brown

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.

New snowfall amounts are unknown at this point, but they can be assumed to be sufficient to produce human triggered and possibly natural avalanches at upper elevations.  Storm snow hazard will decrease along with elevation as above freezing temps have limited accumulations. 4-6 inches of additional snowfall that is forecasted above 2000' will continue to apply pressure to the snowpack.  Wet loose remains a concern, but less so than yesterday as this problem in now confined to below 2000' where there is not very much snow and very thick vegetation will limit the possibility for significant snow entrainment.  

One of many questions that should be looked at while traveling in the mountains today is if their is any reactivity in or around the raincrust that formed on 12/5.  This rain crust formed in the middle of a 12-18" deep storm slab between 3000'-~4500'.  Its current depth will be highly variable due to location and elevation.  Digging snow pits and performing ECT tests (click link for example) will be the most effective way to evaluate this layer.  This layer has not yet been identified as a persistent weak layer, but with a lot of active weather this week it is worth investigation.  

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    0 N/O N/O    22    124 Nicks    0 N/O    40    22 N/O 46 Mile    0   0   14    3 N/O

Régions couvertes