Boletín de aludes

Blues

Wallowa Avalanche Center
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Peligro de aludes

Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Newly formed windslabs exist on leeward east and northeast facing terrain especially near and above treeline and at ridgeline. Evaluate snow stability very carefully on any slopes steeper than 30 degrees that you are considering traveling upon on the aforementioned terrain. If you are unsure about the stability of a steep slope you are considering,  think about doing your recreating on slopes less than 30 degrees in steepness, where you will find a plethora of great snow riding possibilities.

 

This forecast sponsored by the Wallowa County Gamblers

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Windslabs are still the main avalanche concern for today on leeward facing north, northeast, and east facing terrain near and above treeline. The new snow that we received in the early part of the week was accompanied by enough wind to create windslabs. In many  places these windslabs are resting upon surface hoar and surface facets that were observed last weekend. Windslabs resting atop surface hoar and facets will need many days or more to bond to the old snow it rests upon. If you plan to recreate on slopes steeper than 30 degrees today, take the time to evaluate snow stability before committing to that steep slope. Red flags such as shooting cracks, collapsing, whumpfs, and hollow sounding snow you are traveling upon are signs that the snow is unstable and could avalanche. If and when you observe these warning signals, it is suggested that you choose low angle terrain less than 30 degrees steep to do your recreating on.

    (12/21/2022)

    Compression test performed Wednesday morning, Northern Elkhorns. Northeast facing 30 degree slope at 7983' . The top layer was a 6" thick windslab of new snow that fell Monday and Tuesday. The 1" weak layer consisted of surface hoar that formed during the nice weather we had last week. The 1 finger hard bed surface was the old snow that fell about 10 days ago. This Compression Test failed easily on the buried surface hoar layer. The snow depth at this location was 170cm or about 68".

    CT5RP⬇️17(cm)

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    1–3

    Our persistent slab problem is still with us today and into the foreseeable future. Since the weak, persistent grain types that we have been monitoring since late November are now  buried deeply in the snowpack, we are calling it a " deep persistent slab " as opposed to a "persistent  slab" .The weak layers are now buried deeper and therefore are harder to trigger. Because they are deeply buried, the slabs are much bigger and therefore potentially much more destructive than other avalanches. Deep persistent slab avalanches are triggered in areas where the snowpack is thin or shallow. Shallow snowpack areas are found near rocky areas and wind blown ridges. These large, deep persistent slabs can also be triggered from the bottom of a slope. I am seeing these deep persistent weak layers now buried 3' or below the snow surface. It is getting harder to get these deeply buried weak layers to fail in my Snowpit tests. Most Snowpit column tests don't affect layers buried deeper than 3' below the surface. That said, yesterday at Spout Springs I dug a snowpit on an east facing slope. The snow was 3' deep at my pit location. I performed a Propagation Saw Test on a persistent weak layer close to the ground and got the column to fail, exhibiting poor stability at that location. This is just one example of what we have been seeing in the now deeply buried weak layers existing in our snowpack. We are avoiding slopes steeper than 30 degrees for the time being until we see this problem go away, which could take some more time.

    (12/22/2022)

    Weak layer buried 3' below snow surface, close to the ground. Column tests and extended column tests did not affect this deeply buried week layer on this east facing snow pit at 5400' . However, the Propagation Saw Test that I executed produced propagation, revealing poor deep slab  stability at this locations. You can see in the photo the saw handle which is protruding from the weak layer being tested. Test performed at Spout Springs in the Blue mountains.

    PST 40/100 END

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