Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

We're just at the end of a storm cycle. You could still trigger large avalanches, particularly at upper elevations that may have stayed as snow. Travel around steep, unsupported slopes and convex rolls at higher elevations to avoid triggering an avalanche. If you're sinking deeply into heavy, wet snow, move to lower angle slopes. 

Problemas de aludes

  • Storm Slabs

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

    Well over 1ft of snow fell throughout East Central, and you could still trigger large storm slabs at upper elevations. Avoid steep slopes at upper elevations that were less impacted by rain. The new snow fell on slick crusts and weak surface hoar from Friday night. The warm temperatures and rain created an unstable upside-down snowpack with heavier snow on top of softer snow. You can also use quick hand pits and small, steep test slopes to see how easily the new snow slides on the crust. If it slides off easily, that's a good sign avalanches are likely. Slopes over 35 degrees, convex rolls, and areas exposed to the wind are the most suspect spots to trigger an avalanche. Steady winds drifted the snow into deeper slabs, so be particularly cautious to avoid steep slopes below ridgelines. Look for signs of unstable snow, like cracks that shoot away from you or other recent avalanches.

    (12/1/2023)

    Small test slopes like this can be great indicators of unstable storm slabs. 

    Photo: Matt Primomo

  • Loose Wet

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

    Temperatures are forecasted to cool slightly, but we probably aren't putting the snowpack into a solid freeze. So, at lower elevations, you might trigger some small, wet loose avalanches in steeper terrain. Even though the sun is not very strong this time of the year, it may become the tipping point with the mild temperatures. Even smaller wet avalanches might be strong enough to knock you over or push you into trees and rocks. Be aware of the instability, and consider moving to lower-angle slopes if you're sinking deeply into wet, heavy snow. 

    (1/25/2023)

    You may be able to trigger small wet loose avalanches like this until the snowpack gets a solid refreeze. 

    Photo: Katie Warren

Avalanche Discussion

On Saturday evening, upslope winds and an atmospheric river brought 8-20 inches of snow across the East Central. In many areas, snowfall rates hit 3"/hr! Luckily, most of the warmup happened after the highest precipitation rates for most of the zone. Unfortunately, the Salmon La Sac drainage saw much more rain during the event, and reports indicate a saturated snowpack once again. Throughout the zone, folks enjoying the new snow reported a widespread natural avalanche cycle. Mission Ridge Patrol reported 2ft deep wind slabs that rain on the 12/7 crust. We have a lot of uncertainty about conditions at higher elevations. Therefore, as high pressure takes hold this week, approach new terrain slowly. Don't commit to larger slopes before first seeing how the snow reacts on many small, lower-consequence slopes. As you travel, you should carefully observe how well the new snow bonds to the underlying surface. 

Before the storm began on Saturday, we got a chance to get up above 6000ft in the Wenatchee Mountains near Mission Ridge. While lower elevations have a thick melt-freeze crust on the surface, we found that all the rain didn't change the snowpack much at upper elevations in this area of the zone. Very weak snow exists on the base of the snowpack and is producing unstable snowpack test results. With this weak structure, avalanche conditions could deteriorate rapidly and potentially linger for some time. While the Wenatchee Mountains can have a unique snowpack, this weak basal structure could exist in other areas of East Central. The surface hoar and weak bond with the 12/7 could be even more widespread throughout the zone. 

The recent snow fell on bare ground at lower elevations. So, depending on where you go, the chance to hit buried rocks, logs, and other obstacles may still be a significant hazard. 

You can add to the forecast! Please let us know what you see in the mountains by submitting an observation.

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