Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Large wind drifts remain most reactive in wind-exposed upper elevations, particularly where E winds continue to transport snow. Continue to avoid steep, wind-loaded slopes if you travel up high.  Use simple slope tests to identify up to 20" of storm snow that may be slow to heel given bitterly cold temperatures.

 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Crystal and White Passes received 10-20" of snow that was transported by strong to extreme winds through Tuesday night. Slabs 24-48 hours old will be slow to heel with the cold temperatures. You're most likely to trigger them above treeline or in areas where E winds pick up Wednesday night and Thursday. Navigate with caution as you move into more wind-exposed terrain. Snow that seems hollow when you stick an object into it or produces a crack that shoots away from you should be a clear indicator of unstable snow. Continue to be suspicious of all wind-loaded slopes steeper than 35 degrees.

     

    (12/21/2022)

    Example from Mt Hood: Wind slabs under corniced features. Note the wind-textured snow nearby and cornices above the slope to help you identify which slopes to avoid on Thursday.

    Photo: Ryan Matz

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    10-20" of storm snow came in "upside-down" and rests on potentially weaker interfaces that could include surface hoar or near surface facets. White Pass Pro patrol triggered a 15-20" slab on buried surface hoar (12/18).  An avalanche such as this reminds us that you can still trigger an avalanche that could ruin your day on a steep or unsupported open slope near or below treeline. These weak interfaces may heal more slowly given the bitterly cold temperatures.  These slabs may be larger and more reactive where more snow fell in the White Pass. Travelers in the Crystal area reported generally improving stability on Wednesday, but did identify some facets down 15-20" on an E aspect at 6000 ft that could still be reactive. Use lots of simple and quick hand pits or test slopes to continuously evaluate this layer and choose terrain features. Choose slopes of lower consequence without convex rollovers or terrain traps below if you choose to ease into avalanche terrain.

    (12/21/2022)

    Control induced avalanche which failed on buried surface hoar on the Nordic side of White Pass Ski area at 4550 ft, E aspect.

    Photo: Remy Aucoin

Avalanche Discussion

Bitterly cold temperatures and sub-zero wind chills remain a travel concern if you head out on Thursday. Pack extra layers and plan an added margin of safety in your outing given the conditions.

Tuesday’s storm packed quite the punch and delivered over a foot of snow to most areas throughout the West South zone. Accompanying these impressive snow totals were even more impressive winds.  NWAC weather stations recorded gusts into the 70s and 80s both on the volcanoes and near the crest. 

While no avalanches have been confirmed on our older 12/8 buried weak layer in the snowpack, we are still keeping it on our radar for the duration of the week. 

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