Boletín de aludes

Olympics

Northwest Avalanche Center
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Peligro de aludes

Sun
Alta montaña
3 · Notable
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Storm slabs will be most reactive at the start of the day and could be large and easier to trigger in wind-loaded locations. Ease into the terrain, using frequent tests on inconsequential slopes to evaluate the problem.  Avoid steep, wind-loaded, or unsupported terrain features particularly near ridgeline and above treeline.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Heavier-than-expected snowfall on Friday may continue through the night before tapering on Saturday. Observers found 12" of snow well bonded to the Christmas crust on Friday.  Slightly denser snow fell during a period of warmer temperatures on Friday which created a storm slab. That slab lacked the cohesion to propagate across the slope, but was starting to propagate farther in wind-affected locations near ridgelines. With another 4-6" of snow on Friday night, storm slabs will be more reactive and widely propagating. Expect to find 1-1.5 ft of recent snow lying above the Christmas crust by Saturday morning. We expect that trigger points will be limited to specific terrain features such as unsupported or wind-loaded slopes steeper than 35 degrees near ridgeline. However, where drier snow exists above treeline, instabilities will be more widespread and slower to heal. At these elevations avoid all slopes steeper than 35 degrees. Watch for more widely propagating shooting cracks and constantly evaluate small test slopes with a quick slope cut. If you're getting seeing some of these warning signs, dial back your terrain selection.

    (12/30/2022)

    Propagating cracks indicate the storm slab needs more time to settle before you jump on a steep slope.

    Photo: Sam Siemens-luthy

Avalanche Discussion

Around 8" of fresh snowfall on Friday adds to 5" of snow observed on Thursday. Snow was heavy and wet below 4500 ft and changed to rain below 4000 ft. Travel at these lower elevations may not be an option on snow with very limited coverage and wide open creeks. Near treeline, the snow is filling back in quickly, but snow travel remains difficult in thickly treed locations or where more water pooled during the Christmas rains. 

Observations from 12/28 illustrate significant wind transport of the denser snow that has bonded well to the Christmas Crust.

At higher elevations on Saturday, sun breaks could lead to a round of mostly small wet loose avalanches on steep slopes facing the sun. Adjust your aspect and reduce your exposure if the snow starts becoming sticky and wet.

It's been wonderful to see all the observations flowing in from the Ridge and beyond this Holiday season. They are really helping to improve the forecast!

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