Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

You could trigger avalanches in freshly wind-drifted snow that could step down to deeper layers and become very large, breaking widely across terrain features. We don't have much information from East South, but these deeply buried layers are producing very large avalanches in adjacent zones. Stick to low-angle slopes in simple terrain to avoid triggering a dangerous avalanche. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–2.5

    Blustery conditions will return to our mountains and quickly form fresh wind slabs on lee aspects. Identify wind-loaded features with visual clues like actively blowing snow, cornice formations, and textured surfaces. Avoid steep slopes where you find these stiff, wind-drifted slabs. With 2-3ft of fresh snow in the last 48 hours, these avalanches could easily be large enough to bury, injure, or kill a person. These avalanches could also step down to more deeply buried weak layers and become very large, propagating across terrain features. Look for signs of instability, such as collapsing, cracks that shoot away from you, and recent avalanches. These are all indications that you are likely to trigger an avalanche. At lower elevations with a thinner snowpack, avalanches might be smaller, but they would carry high consequences if you are dragged through terrain still riddled with rocks, stumps, creeks, and other terrain traps.

    (1/7/2024)

    At upper elevations, moderate ridgeline winds were actively drifting snow. These winds decreased to light and variable by the afternoon. 

    Photo: Katie Warren

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    You could trigger a very large persistent slab avalanche on various layers now buried 2-4 feet deep. These avalanches can propagate widely around terrain features, and you may be able to trigger them from adjacent lower-angle slopes. The best way to manage this avalanche problem is to simply avoid steep open terrain. Instead, seek out low-angle, simple terrain. Before this storm, there were numerous close calls with avalanches on these persistent weak layers. Post-storm, these same layers are buried much deeper and continue to produce avalanches. Mission Ridge Ski Patrol triggered multiple avalanches that failed on weak, faceted snow over the Solstice Crust, and a backcountry traveler near Lake Wenatchee remotely triggered a small avalanche on a steep convexity on this same layer. White Pass Patrol and Crystal Mountain Patrol also triggered very large avalanches on persistent weak layers on Tuesday.  Buried surface hoar (1/2) was responsible for two other human-triggered avalanches before this storm. We have yet to hear about more recent avalanches on this layer, but it could still be an issue. With both layers potentially lurking below the surface, extra caution and wide safety margins in your travel plans are warranted. 

    (1/10/2024)

    Backcountry travelers near Lake Wenatchee remotely triggered this avalanche from a low angle adjacent slope. This avalanche ran on weak, facted snow over the Solstice Crust.

    Photo: Pat Riffie

Avalanche Discussion

We may get another dusting of snow on Thursday, but the main event will be increasing winds. It will probably feel like a stormy day in the mountains, and avalanches could become more likely as winds increase in the afternoon. Southern slopes warmed in the sun on Wednesday and now have a thin, breakable crust on the surface. A bump in temperatures overnight on Monday means that elevations below 4000ft likely saw some rain before quickly transitioning back to snow, and now, we have a new melt-freeze crust in the middle of the storm snow. This melt-freeze crust showed a poor bond and potential for propagation in East Central on Wednesday. 

Lower elevations likely have significantly better coverage after Tuesday's storm, but the coverage is still below average. These elevations may not quite meet the threshold for large avalanches. However, you could still trigger a smaller avalanche with serious consequences from hitting exposed hazards like rocks, stumps, or downed trees. 

If you get out let us know what you see by submitting a public observation!

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