Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

Look out for accumulations of fresh, wind-deposited snow at higher elevations. Stick to conservative terrain to lower the risk of triggering a large slab avalanche with potentially serious outcomes.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–2.5

    Although the chance of triggering a large avalanche is declining, a weak layer of faceted snow still exists 2–4 feet below the surface. The same layering is the likely culprit in natural and human-triggered avalanches last weekend. No new, large avalanches were reported in the last six days.

    The likelihood is pretty low - but not impossible - that you could trigger one. If you do it would probably be in wind-scoured areas with less new snow over the weak layer, on unsupported slopes like steep convex rolls or slopes above cliffs, or in less traveled or remote terrain.  A heavy load like multiple snowmobiles, large groups of people, or big cliff drops might trigger an avalanche where the load of a single person or sled would not. 

    If you want to completely avoid triggering a large avalanche, stay off steep slopes. If heading into avalanche terrain choose more planar, moderately inclined slopes with clean runouts free of obstacles like rocks, cliffs, or gullies.

    (3/2/2024)

    Avalanches that fail at a layer of buried facets tend to be deeper and propagate wider than the typical new snow slab avalanche.

    Photo: Dallas Glass

  • Wind Slabs

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

    Some upper-elevation areas saw enough wind to drift snow and form small slabs. Also, a small slab avalanche was reported from alpine terrain on Friday. There might be a few more out there to find if you are headed to similar terrain.

    Keep an eye out for rippled, textured, or scoured surfaces, cornices, and wind lips—they’re signs that fresh, wind-drifted snow might be present. Watch how the snow’s firmness changes to figure out if there is wind slab lurking nearby. Use simple tests like hand shears or small-slope cuts to check the bond of wind slabs to the layer below.

    (1/15/2024)

    Textured snow and small cornices are clues you could find wind slab on the shaded slope in this photo.

    Photo: Andy Harrington

    Phil Straub

Avalanche Discussion

A snow immersion accident resulting in a fatality occurred in backcountry terrain on Wednesday. Keep your partners in sight at all times. Stay close enough to help them if they get buried in a tree well or some other deep snow hazard.

Loose snow at the surface is becoming more cohesive and less likely to slide. But it’s still loose and could produce small avalanches, especially once it gets going in steep terrain with long sustained fall lines. Stay alert to snow moving with you downhill if descending or side-hilling steep slopes. Afternoon sunbreaks could get snow to shed from cliffs and trees which can in turn trigger loose snow avalanches on slopes below.

Very good riding conditions are still found in most areas with the exception being southerly slopes that hold a bit of crust at the surface. On average there's three or more feet of right-side-up snow over the old snow surface buried on January 30th. This snow sits directly on crust in terrain that saw strong sun and warming from January 26th through 29th. On more shaded slopes, the new-ish snow lies over a layer of faceted snow over a crust - now decomposing - that formed earlier in January.  More faceted snow is found below these crusts on all aspects. Avalanche activity related to these layers peaked last weekend. Snowpack testing still points towards propagation in layers of faceted snow. 

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