Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

Morning Update: Updated middle elevations to moderate danger due to overnight winds and slightly more snow than initially expected.

East winds loading atypical aspects remain the main story, along with increasing danger as you ascend in the terrain. Look for plumes of snow near ridgelines, covered tracks, and fresh sharp cornices alerting you to the steep slopes where you can trigger a slab.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Mostly small wind slabs will be reactive to human trigger near ridgelines in areas exposed to the E winds. Expect these winds to increase Wednesday night, transporting snow and forming fresh drifts that will increase in size and coverage as you ascend in the terrain. Winds should gradually decrease on Thursday. Locations farther east in the zone such, channeled valleys, and exposed foothills should feel the brunt of these winds. Significant amounts of dry snow remain available for transport on the northern half of the compass, while sun crusts on other aspects hold dry snow in place. Wind speed, small amounts of new snow, and the amount of loose snow available for transport will likely be the two variables that determine avalanche danger.

    Snow plumes off ridges and fresh, sharp cornices point toward the hazard on the slopes below. In some areas, winds may cross-load slopes with softer snow. Drifts may form in gullies, and below steep rocky features. You might be able to pick up on the different textures between wind-stripped and wind-deposited surfaces in this case. Signs of wind transport include active snow transport and variably covered tracks, provide additional yellow flags to slow down and evaluate the wind loading patterns in your terrain.  Hand shears and test slopes on small, wind-drifted features can give you a sense of slab reactivity. Steer away from steep, wind-loaded slopes in exposed terrain, noting that these may be on slopes you don't typically expect to find a slab.

    Example: Wind drifted snow and fresh cornice formation along Ptarmigan Ridge.

    Photo: Michael Bartley

Avalanche Discussion

Wind slabs and dry loose will be your primary concern given the cold temperatures and these problems will stick around. Lingering weak layers also remain in play.  Snow surfaces continue to weaken. These could make shallow wind slabs touchier than you might expect.

 Observers on Ruby Mountain Wednesday, reported 8-10" of snow poorly bonded to a firm interface. They triggered multiple dry loose avalanches on very steep terrain, confirming the ongoing dry loose hazard.

Observers at mid-elevations have found that the storm layers are generally bonding well, and faceted snow below the new snow doesn’t seem to be an issue. But small natural and human-triggered slab avalanches were reported from upper elevations on Monday. Areas that experienced cooler temperatures and/or less wind during the last storm might have slightly weaker layering. 

You might also see some evidence of wet loose activity from sunny skies at times Monday through early Wednesday.

 

 

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