Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

“It’s DEEP!” seems to be the common refrain from most travelers. Even as the snowpack continues to heal and avalanches danger declines, keep your eyes peeled for pockets of wind-loaded snow at mid and upper elevations. You could still trigger an avalanche on steep slopes below cornices or underneath cliffs.

Lawinenprobleme

  • Wind Slabs

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

    The wind slab problem will transition Friday from the potential for older large avalanches to newly forming thin slabs. You’ll need to manage both as you travel. During this last storm shifting winds likely drifted snow onto a variety of aspects. Now a blanket of soft powder hides these lingering and harder-to-trigger slabs. Look for cornices and drifts behind objects to help you anticipate which slopes could still harbor one of these bigger and more dangerous avalanches. 

    As the winds shift and strengthen during the morning you may notice blowing snow forming new avalanche concerns. Fortunately, this type of wind slab will be easy to spot and relatively small. The wind direction and actively transporting snow should help you observe this problem. While we expect them to remain small, they could trigger easily. Don’t let them take you for a ride through high-consequence slopes.

    (12/1/2022) Rime and wind drifts can help you anticipate wind loaded slopes. Photo: Dallas Glass

Avalanche Discussion

After several days under the fire hose, the West South should enjoy a break in the weather Friday. This should allow the snowpack to heal and the avalanche danger to decrease. The last few days (since 11/29) locations around the zone received 30-40 inches of snow (2-3 in SWE). This grew the snowpack by 20 inches for most areas and more than doubled the snow depths at lower elevations. Needless to say, not bad for a late November storm. 

Natural slab avalanches were reported during the height of the storm early Wednesday morning. These occurred within the new storm snow, and some of them were well below treeline. On Thursday, Crystal Mt Ski Patrol triggered a very large avalanche on older snow layers (likely the 11/22 interface, see photo). This combined with 2 other deeper explosive-triggered slides reminds us that early-season snowpacks are highly variable. The common thread among these slides seems to be relatively high elevation(>6500ft), northerly facing, wind-loaded terrain. While very unlikely, there is at least some potential to find one of these isolated pockets and trigger a very large dangerous avalanche. 

With all this new snow, don’t take the decreasing and “Low” hazard to mean “no” danger. You may still trigger small loose dry avalanches on very steep slopes. While these sluffs are often easy to anticipate and manage, don’t let them carry you into high-consequence terrain. Open creeks, holes around rocks, and plenty of small trees make most slopes much more hazardous during these periods of early season conditions. With all the deep powder and obstacles, keep your partners close and give yourself extra time to navigate through these hazards.

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