Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

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

Happy New Year! Time your travel to be off of steep, sunny slopes before wet avalanche activity begins. If you see widespread avalanches or some that are big enough to bury you, anticipate dangerous avalanche conditions. Elsewhere, you may still be able to trigger avalanches in recent snow 1-2 feet below the surface.

Problemi valanghivi

  • Loose Wet

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

    Expect the sun to warm steep southerly slopes and to trigger wet avalanches. These avalanches typically form more readily on steep rocky terrain or near cliffs. Plan to travel uphill in areas free of steep sunny slopes overhead. As the day warms, you can avoid these avalanches by sticking to more shaded, northerly aspects.

    While we know these avalanches will happen, it's uncertain how widespread they'll be an if any will be big enough to bury or kill you. Pay careful attention to any avlalanche activity. If you see avalanches big enough to bury you or widespread activity, consider that you're dealing with dangerous conditions. In this case you may want to avoid all steep, southerly terrain.

  • Storm Slabs

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

    You may still be able to trigger avalanches in the top 1-2 feet of the snowpack. Use small test slopes and quick tests to check how the new snow slides. If you see cracks in the snow or test slopes that slide easily, steer around typical trigger points and steep slopes. This includes unsupported slopes, convexed rolls, and rocky slopes over 35 degrees.  

    On leeward sides of ridges near and above treeline, you may be able to trigger wind slab avalanches where you find areas of deeper snow accumulation and wind-stiffened snow. If you see signs of previous wind drifting or cracks shooting through stiff snow, use extra caution. You can stay safe by steering around steep slopes and drifted pillows of snow. 

    (12/30/2022)

    A natural slab avalanche with a crown over 200ft wide. Skyline/Moonlight area E, 4,600ft

    Photo: Liz Riggs-Meder

Avalanche Discussion

On Saturday, snow surfaces were moist below treeline. Matt Primomo reported light wind affect on a ridge of Mt McCausland, a small wet avalanche, and dangerous tree bombs (blocks of snow falling from trees).  Observer, Brooke Maushund, reported some small wet avalanche on steep slopes below 4,000ft at the pass and up to 5,000ft on the eastern edge of the zone where more sun broke through the clouds. An observer in Henry Creek noted blowing snow was visible on the summit ridge of Jim Hill. 

On  Friday and Wednesday, observers reported very reactive avalanches with multiple shallow natural and triggered slides in the new snow. One natural avalanche in the Skyline/Moonlight area had a crown that was over 200 feet wide and may have broke down to the Christmas crust. See photo above. Some of these interfaces may still be able to produce avalanches as mentioned above. From December 23-27th the Schmidt Haus weather station measured nearly 5.5" of water equivilent with heavy rain and sleet forming a stout crust. The Christmas crust is now 2-2.5 feet (50-75cm) below the surface.

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