Lawinenlagebericht

East Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Rising freezing levels and sunshine will thaw the snowpack over the next 24 hours. Dangerous conditions exist with a mix of wet and dry snow avalanche problems. You could easily trigger large avalanches on slopes greater than 30 degrees at all elevations. Choose simple terrain and don't linger in the runout zones of large avalanche paths.  

Lawinenprobleme

  • Loose Wet

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

    Freezing levels are expected to skyrocket to 8000ft on Sunday with another round of sunshine. A temperature inversion may set up with cold air pooled at lower elevations and the warmest air above. The dry snowpack will experience a rapid thaw, and a wet loose avalanche cycle is expected. These avalanches could be dangerous on their own, or even trigger slab avalanches as they run dowhill. You should steer around any large steep slopes by the time snow surfaces are wet and unconsolidated. If you see rollerballs, pinwheels, and snow shedding from rocks and trees, expect wet avalanches to soon follow. Keep your return routes in mind, and head home early if the snowpack turns to mashed potatoes under your skis or sled.

    (3/27/2021) Example photo of wet loose avalanches you will likely encounter on Sunday.

  • Wind Slabs

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

    All the recent snow still needs time to settle and stabilize, especially in wind-loaded areas. The thickest and most reactive slabs exist above treeline. Even though the likelihood of natural slab avalanches decreased, slopes 30 degrees and steeper are primed for human-triggered slides. These avalanches could even break deep, wide, or be triggered from a distance. Carefully assess the snowpack as you travel looking for recent avalanches, shooting cracks, and collapses. Be especially careful around rocky areas and rollovers. Limit your exposure to overhead hazard and stick to simple terrain sheltered from the wind.

    (1/7/2022)

    Blowing snow and wind-loading in the snow-covered hills above Naches on Hwy 12.

    Photo: John Stimberis

Avalanche Discussion

Another deep persistent slab avalanche was triggered with explosives at Mission Ridge Ski Area Saturday, similar to the avalanche from Monday. Both of these slides ran on weak snow associated with the crust buried on the winter solstice. A very large explosive triggered avalanche occurred at Crystal Mountain on Friday and broke on weak snow at the ground. Although we have high uncertainty and a lack of observations, similar snowpack conditions with these problematic layers could exist throughout the East South Zone. Be very cautious if you head out into the mountains and build in a wide margin for error.

The most significant storm so far this season just ended. Avalanche cycles have been ongoing and will transition to a wet character with the big warm-up Sunday. These are unusual conditions with avalanche hazard extending to lowland areas. Avalanches closed Highway 10 and Yakima Canyon Road Thursday, and Highway 12 remains closed. Many roof avalanches were reported throughout the region as well, including an incident in Roslyn where an 80 y/o man was fully buried in a roof avalanche on January 7. Fortunately, his wife witnessed the event and called 911. Roslyn fire was able to dig the man out of the debris. He sustained only orthopedic injuries. 

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