Avalanche forecast

Southern Wallowas

Wallowa Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

It remains likely that you could trigger a large deadly avalanche failing on weak snow 2-6 feet deep.  Large natural avalanches have occurred in the last 6 days.  Increasing winds throughout the day will build sensitive wind slabs in exposed terrain.  If you are keen to not be in an avalanche, stick to low-angle slopes, avoid avalanche runout zones, and avoid wind-loaded terrain.

Avalanches will be more likely around Fish Lake, Sugarloaf, Clear Creek Cabin, Norway Basin, and adjacent drainages where the past week's snowfall has been more substantial than that of the Southwestern Wallowas (Catherine Creek Snopark Area).  

This forecast is sponsored by Anthony Lakes Mountain Resort.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The snowpack structure in the Southern Wallowas is poor and was overloaded by 5" of snow water equivalent over the past week.  The new snow load and wind-blown snow produced many large natural avalanches.  As the skies cleared yesterday, ski guides from WAH observed widespread persistent slab natural activity from the last week.  Check out their observations here and here.  

    ECMG ski guides in the Southwestern Wallowas observed a couple of new avalanches that likely failed 1-2 feet deep on a layer of facets that failed between two melt-freeze crusts.  Check out the observation here. 

    Forecasters rode up to Fish Lake on Wednesday, and despite having limited visibility, it was impossible not to see the large D2.5 natural avalanche that ran across FS RD 66 in an area locals call Avalanche Alley.  (6800' NE aspect).  The crown of this avalanche was 4 feet deep and failed on small-grained faceted snow that sat above a thin crust.  Check out the observation from Wednesday here. We also observed the toe of the debris from a large natural avalanche that reached the elevation of Fish Lake (East aspect).  

    Recent natural and remotely triggered avalanches should be all of the bulls-eye data you need to dial back your terrain choices.  If you want to avoid avalanches, you should stay off of slopes greater than 30 degrees, stay well clear of avalanche runout zones, and not ride above terrain traps.  Don't trust these facets until they are swimming in the river!  

     

    (1/25/2024) Photo: WAH

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    As winds increase ahead of the warm front today, expect to see sensitive wind slabs up to a foot deep in exposed terrain.  You will likely find these at mid and upper elevations along exposed ridgelines and cross-loaded mid-slope terrain features.  Be observant for a rippled and stiff snow surface, and cracking from your boards or machine.  Cornice development may be evident on the leeward sides of ridgelines.  A cornice or wind slab failure could be enough weight on the right slope to trigger a deeper more destructive persistent slab avalanche.  

     

    Photo: WAH

    Cornices and wind slab development have been observed on leeward ridgelines and cross-loaded terrain features.  

Avalanche Discussion

The recent widespread natural avalanche cycles should be all the evidence you need to dial it back! 

As the 4-6 foot slab continues to strengthen and become even more cohesive, the weak sugar snow lurking near the bottom of the snowpack will continue to be a real threat.  We are starting to see less consistency in our snowpack tests, with some tests not showing propagation.   Remember that the poor snowpack structure always trumps a "false negative" snowpack test.  Snowpack tests are not decision-making tools, and offer a single data point in a sea of spatial variability.  It's becoming less evident if you just look at the snow surface, as obvious signs of instability may not be present.  The cracking and whumphing (collapsing) that we observed last week has decreased, and the slab may be able to hold the weight of a rider until the slab thickness decreases somewhere in the terrain.     

Seeing tracks on a slope does not mean it is safe to ride.  Persistent slabs are notorious for allowing unsuspecting riders to lay numerous tracks without incident before one unlucky rider finds a thin spot in the snowpack, collapsing the weak layer and creating a large, destructive avalanche.  Common thin spots in the snow often develop around rocky steep rollovers, or where the wind has stripped snow from the up-wind (windward) sides of ridgelines. 

Now is not the time to push the terrain.  Patience is the name of the game with persistent slabs.  Read the forecast in its entirety, make a conservative travel plan that allows for wide terrain margins, use clear communication with your partners, listen to your gut, and speak up.  

We appreciate all of the observations that have been coming into the WAC from all of our zones.  It truly adds value to your forecast.  Keep 'em coming! Submit your obs here. 

Kelly McNeil will bring you the forecast through the weekend.  Expect some changes with warming temps and rising snow levels.  

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