Lawinenlagebericht

Northern Wallowas

Wallowa Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

It remains likely that a rider could trigger a large deadly avalanche failing on buried weak snow 2-4 feet deep.  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.

This forecast is sponsored by Anthony Lakes Mountain Resort.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    The snowpack structure in the Northern Wallowas is poor.  Many natural and remotely triggered large and very large avalanches ocurred last Sunday.  While the likelihood of more natural avalanches has decreased, the potential is there for a rider to trigger a large to very large avalanche in the right terrain.   Observations from yesterday in the Northern Wallowas indicated that the weak snow at the January 4th interface is starting to gain some strength- but it is still not to be trusted.  This weak snow is found between 2'-4'  from the snow surface.  All of the snow since January 4th has consolidated into a dense slab and sits above this weak interface.  To add insult to injury, the snow near the ground from earlier this fall through December is showing fewer signs of strengthening.  It remains a real threat.  Check out my observations and snowpack tests from yesterday in this video.  

    On Sunday the 21st, there was a large remotely triggered avalanche that occurred in South Bowl minutes after several skiers had skinned across the start zone.   Thanks to the group for being so willing to share details of this near miss. 

    That same day, two other large natural avalanches occurred in the Wing Ridge area.  One in 1st Bowl, and one in 2nd Bowl.  All of these avalanches would have likely been unsurvivable if you were caught in them.  Check out Nick Burk's observation from looking at the South Bowl avalanche on Tuesday here. 

    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!  

     

    Impressive natural D3 avalanche in 1st Bowl. 

    Estimated date of avalanche: 1/21/24

    Photo: Caleb Merrill

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    There is still some snow on the surface to be transported by the wind.  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.  

    (1/11/2024) Photo: Caleb Merrill

Avalanche Discussion

As the 4-5 foot slab continues to strengthen and become even more cohesive, the weak sugar snow will continue to be a real threat.  I suspect this will be the trend as we introduce warmer temperatures this weekend.  As time progresses, this problem will have a lower likelihood, but the consequences will remain real.  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. 

Towards the end of today and into the weekend as our temperatures warm and our freezing levels rise, wet loose avalanches in terrain steeper than 35 degrees will likely occur.  You may notice a cohesionless snow surface from warming or rain.  If you step off your machine or out of your skis, and are sinking to the top of your boot, it's time to scoot! 

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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