Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Another round of light rain and snow will maintain concern for both wet and dry snow avalanches. Be especially careful around wind-loaded slopes at upper elevations where you could trigger large avalanches that break widely across terrain features. Choose simple slopes less than 30 degrees if you observe cracking, collapsing, or recent avalanches.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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 may be ripe 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 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

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    A chance for light rain Monday may be enough to cause wet avalanches at the lowest elevations. These avalanches could be dangerous on their own or even trigger slab avalanches as they run downhill. You should steer around any large steep slopes where you find wet and unconsolidated snow surfaces. If you see rollerballs, pinwheels, and snow shedding from rocks and trees, expect wet avalanches to soon follow.

    (1/9/2022) During the storm warming temperatures and rain produced a wet loose avalanche cycle and created rain tunnels on the snow surface near and west of the Cascade crest, like you can see here on Sprial Butte, White Pass, WA. Photo: Katie Warren

Avalanche Discussion

NWAC and WSDOT avalanche forecasters traveled the Hwy 12 corridor Sunday documenting the recent avalanche cycle (OBSERVATION). Many large slab avalanches ran naturally in new and wind drifted snow. Small to large wet avalanches also ran on many lower elevation slopes. Slab avalanches were even observed in the low-land hills with shallow snowpacks near the Hwy 410/ Hwy 12 interchange.

A second 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 uncertainty, similar snowpack conditions with these problematic layers could exist in the East South Zone. Be very cautious if you travel to upper elevations and ease into terrain slowly.

The most significant storm and avalanche cylcle so far this season just ended. These were 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 orthopedic injuries. 

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