Lawinenlagebericht

Northern Wallowas

Wallowa Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Human-triggered avalanches are likely today in areas where a slab overlies weak faceted snow.  You could trigger a large avalanche on terrain features >30 degrees that have received recent wind loading. To avoid avalanche hazard, stick to slopes <30 degrees and avoid traveling below avalanche runouts.   

This forecast is sponsored by Anthony Lakes Mountain Resort.

Lawinenprobleme

  • Wind Slabs

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

    Yesterday, moderate afternoon winds built reactive wind slabs on exposed features near treeline and above. Several observations reported whumfing and shooting cracks in areas of wind deposited snow.  If you see signs of wind slab activity such as dune-like formations, a textured snow surface, or shooting cracks, avoid slopes >30 degrees.  Adding a slab along with a trigger to our poor snowpack structure could trigger an avalanche larger than anticipated.  

    Reactive shooting cracks along Wing Ridge, ENE at 8200' 2/8/25. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    January's long high pressure weakened the upper snowpack and created several layers of incohesive facets that are now buried 1.5-2.5 feet thick across the forecast area. On southern aspects, these weak grains exist beneath sun crusts. While evidence of this instability may be sparse, the poor structure of the snowpack is not to be trusted. Currently, February's storm snow is slowly settling into a cohesive slab, and reactivity will increase in areas where wind slabs sit atop this poor structure. Patience will be required, as the only way to truly avoid avalanche risk is to avoid avalanche terrain and recreate on slopes under 30 degrees. 

    This natural avalanche was observed in the Southern Wallowas yesterday, with a reported crown of 5'. 

    Photo: Kevin Cassidy

Avalanche Discussion

Winds in the Northern and Southern Wallowas have been subtly outperforming the forecast in previous days, demonstrating that it doesn't take much wind to move the abundant light snow available for transport. Moderate winds forecasted for the afternoon hours will certainly continue to build reactive slabs. Check out these observations for more details (1, 2). In the Southern Wallowas, forecasters discovered buried surface hoar at the 1/31 interface, leading to propagation in snowpack tests in sheltered areas below treeline.

This observation from yesterday highlights the potential complexity of our snowpack - a natural avalanche roughly 50m wide suspected to have failed in the previous 24hrs, likely in an area where winds had deposited enough snow to create a strong (and heavy) slab above weak structure. 

What to do:  Persistent slab problems are notoriously difficult to manage due to a lack of feedback. You may not observe any signs of instability. Natural persistent slab avalanches are rare after the initial loading period. Slopes capable of avalanching may even already have tracks on them. Until the snowpack structure improves the only way to eliminate the risk of avalanches is to avoid terrain steeper than 30 degrees, especially with the potential for overlapping avalanche problems. 

Add value to your avalanche forecast.  Help us reduce uncertainty.   If you get out today, please submit an observation sharing where you traveled and if you saw avalanches or signs of instability. 

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