Bulletin d’avalanche

Northern Wallowas

Wallowa Avalanche Center
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Danger d’avalanche

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

Points saillants

You can trigger an avalanche that will be big enough to bury or kill you today in areas where the wind has blown the new snow into dense slabs.   Recent avalanches, blowing snow, and shooting cracks are all signs that newly drifted snow is primed to avalanche.  Avoid steep terrain that has been loaded with new snow by the wind.  It will also be possible to trigger avalanches in wind-sheltered locations where storm snow amounts are greater than 6".

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Problèmes avalancheux

  • Wind Slabs

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

    A fresh round of wind slabs will be sensitive to the weight of riders today.   To make the problem even less manageable, there are several "generations" of older wind slabs that could still be reactive, but are being covered by new snow (or new wind slabs).   A new snow avalanche could possibly "step down" into an older wind slab and create an even larger, more destructive avalanche.  

    Good clues to wind loading are cornices along ridgelines, rippled and textured snow surfaces, cracking around your skis, and recent avalanches.   Recent natural wind slab avalanches have been observed in the Northern Wallowas in the last two days.  Strong winds can load slopes lower than just along ridgelines.   Keep an eye on mid-slope features lower down from ridgelines that could be cross-loaded and be primed to catch you off guard.  Where possible, utilize small but steep test slopes to test the reactivity of newer or older wind slabs. (think no taller than a single-story house with no terrain trap below).  

    Avoid terrain that is or has been loaded with wind-blown snow and stay out from underneath avalanche paths and runout zones. 

    We have simplified the avalanche problems today into just wind slabs, but avalanches are still possible out of wind-exposed areas.  Wherever you find more than 6" of storm snow that is settling into a cohesive slab, be weary of triggering a storm slab avalanche. 

    (12/26/2024) Textured Snow and shooting cracks are clear signs of unstable and wind loaded slopes.  

Avalanche Discussion

What is it?   Dangerous avalanche conditions will be the norm for the day as significant snowfall rates combine with wind to produce sensitive wind slabs.  Since the start of this storm train, the mountains of Northeastern Oregon have seen a significant load of snow to our snowpack.  Even with a relatively strong snowpack, this is a big load.  Today very well could be the day when the scales are tipped.  The new snow and wind-blown snow will be waiting for a trigger whether it is a rider or just the weight of new and wind-blown snow.  You don't want to be the straw that breaks the camel's back.  

See below for storm snow totals and snow water equivalent(SWE) totals since Christmas Night.  

Blues: 16"/2.2" SWE (High Ridge Snotel)

Elkhorns: 17"/2.3" SWE (Bourne Snotel)

Northern Wallowas: 10"/1" SWE (Aneroid #2 Snotel)

Southern Wallowas: 27"/3.5" SWE (Schneider Meadows Snotel)    13"/2.3" SWE (Taylor Green Snotel)

Where is it? You will be able to find unstable snow in many locations today.  Today is not the day to toe the line.   If you do decide to travel near or in avalanche terrain, wide terrain margins will be essential.  You can most likely trigger a large avalanche on wind-loaded slopes steeper than 30 degrees.  You will most likely encounter wind-loaded slopes at mid and upper elevations, on most all aspects.    In wind-sheltered areas- if you find new storm snow in the 6-8" depth range, you could potentially trigger a storm slab avalanche.  

What to do about it?  Well, it will likely be a pretty nasty day to be out in the mountains with the ongoing intense storm.  It might just be a good day to start brainstorming about some New Year's resolutions, start that new book that your friend gave you, or watch a classic holiday flick.    If you do head out into the hills, I would suggest having a conservative mindset, avoid potential avalanche paths that may be above or adjacent to your intended route, and testing the reactivity of new snow by utilizing small and inconsequential test slopes.  If you see a cohesive slab of snow break at your machine or boards, you can bet that triggering an avalanche on a larger slope is likely.  

What's going on a bit deeper? A destructive and deadly scenario that I can imagine happening today is a fresh wind slab avalanche being triggered that could add enough weight to "step down" into an older interface of snow from either the last 4 days of wind slab development or into even deeper layers of the snow (think Thanksgiving Drought Layer).  Older windslabs that may be still sensitive will be hard to identify without jumping off your machine or stepping out of your boards and digging down at least 2 feet to see if you see strong over weak snow in the layers of the snowpack. 

Check out the most recent observation from the Northern Wallowas here. 

Help reduce the uncertainty of your avalanche forecast.  If you get out into the backcountry today, let us know what you are see by submitting an observation here.  

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