Bulletin d’avalanche

Northern Wallowas

Wallowa Avalanche Center
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Danger d’avalanche

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

Points saillants

It remains possible to trigger a very large avalanche breaking 2-6' deep in the snowpack. Fresh snow has created storm slab instabilities. Triggering an avalanche in the new snow could be enough of a trigger to cause an avalanche deeper in the snowpack to release. Staying off slopes steeper than 30 degrees is advised to avoid triggering an avalanche.

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Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3

    The snowpack in the Northern Wallowas is currently weaker than the other forecast zones. Despite the warm weather and rain, poor snowpack structure still exists. The possibility of triggering a persistent slab avalanche is still a very real one. The slab of snow sitting above the weak layers has gotten more dense due to recent weather. Triggering an avalanche would have serious consequences. If you want to avoid avalanches you should stay off of slopes greater than 30 degrees. 

    In my travels yesterday in the Northern Wallowas I had propagating fractures in both Compression and Extended Column Tests in the November/December snow despite a 7cm/2in thick crust under the new snow.

      

    (2/1/2024)

    The orange line shows the weak snow causing the persistent slab problem.

    Photo: Caleb Merrill

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    8-12" of fresh snow exists above 7000'. Another 2-4" is forecasted for today.  This snow rests atop a melt-freeze crust. In my travels yesterday I found the bond between the old and new snow to be good. As the snowfall totals stack up the likelihood of triggering a storm slab increases. The new snow is hiding some shallow, more dense wind-affected snow around ridge tops on all aspects.

    Fresh snow begs to be tracked, especially after two weeks with no new snow. Remember that this fresh powder lies on top of a dangerous snowpack. If you are on a slope steep enough to trigger a storm slab, it's also steep enough for a persistent slab.

    (1/11/2024) Photo: Caleb Merrill

Avalanche Discussion

Continued snowfall today will increase the amount of snow available for a storm slab avalanche. The new snow is hiding some shallow, more dense wind-affected snow around ridge tops on all aspects. Forecaster Caleb Merrill posted this observation showing reactive stability test results on the weak snow from November/December 2/1 in the Northern Wallowas. I found similar results yesterday 2/2. All these factors make for a complex environment to travel through. When the complexity and consequences are high, it's best to keep it simple and choose terrain less than 30 degrees.

The past two weeks have been warm and the mountains have received some rain. Large wet slides have been observed. This has changed and consolidated the snowpack. While the overall stability trend is headed in a good direction it is still possible to trigger a very large avalanche breaking 2-6' deep. The poor snowpack structure still exists. Continued vigilance is necessary to avoid getting caught in a powerful destructive avalanche.

 

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Saturday, Feb 3rd-

  • Kip Rand Memorial Backcountry Race 8 am 
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  • 1 PM Snowpack assessment clinic
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Sunday, Feb 4th-

  • Backcountry ski tour into Angell Basin

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