Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Wed
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

Calmer weather is in store for Tuesday as the latest storm moves through the Cascades. Steep terrain holding areas of wind drifted new snow will again be the main danger as you gain elevation to treeline and above. Use caution on downwind slopes and stick to lower-angle terrain where you observe signs of wind affected snow. Sunny skies could give rise to small wet avalanches, especially south of Hwy 2.

Lawinenprobleme

  • Wind Slabs

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

    Wind slab, wind slab, and more wind slab has been the theme for days. Snowfall and strong winds should taper on Tuesday, but overnight they will have been hard at work churning out another batch of new slabs. You will likely find calmer weather and maybe even some sun in the mountains tomorrow. But the fresh slabs - and even some of the day-old ones - need some time to stabilize on steep slopes.

    Soft new snow might obscure the clues you normally use to identify loaded slopes. Gauge the depth and stiffness of the top layer of snow to find wind slab. Use simple tests like hand shears and test slopes to assess the bond of wind slab layers as you gain elevation. 

    There is a greater chance of triggering a wind slab on convex breakovers or other unsupported terrain features like hanging slopes above or around cliffs and rock bands. Avoid these features to reduce risk.

Avalanche Discussion

Slowly clearing skies could add some sun to a rise in temperatures Tuesday. This will be more the case the farther south you are in West Central. Stay tuned into warming conditions and look out for the usual signs of wet loose avalanche activity like pinwheels, rollers and very small avalanches. There’s a lower likelihood of seeing larger wet avalanches but it’s worth keeping track of what is going on above you. Minimize your exposure to steep slopes where you see signs of instability listed above.

An NWAC Forecast team ventured into the southern Mountain Loop area. The most noteworthy observation was extensive wind transport in alpine terrain. While less transport was found at treeline, there was still enough snow and wind to build shallow but reactive wind slabs on loaded slopes. A firm crust topped the snow surface to 4000'. Above that elevation, the amount of new snow over the crust quickly increased as they gained elevation. There was about 1' of new snow that fell over the last four days. The sun warmed solar aspects enough that you might find a crust on the same aspects tomorrow morning.

Less wind transport was observed in Stevens and Snoqualmie Pass as those areas received less snow the past 24 hours. Reactive new wind slabs were found but they had a lesser distribution and tended to be quite small. The opposite was the case in West North where up to 10" of new snow was widely redistributed by gusty winds. A handful of human triggered wind slab avalanches - some approaching D2 in size - were reported. 

 

 

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