Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

You can still trigger large avalanches near and above treeline where the wind built fresh slabs of snow earlier this week and will continue to form drifts into Friday. Use caution on slopes over 35 degrees, especially where the wind has drifted recent snow into deeper slabs. Continue to give the snowpack some time to adjust to the recent snow before traveling in steep, consequential terrain.

Lawinenprobleme

  • Wind Slabs

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

    Use caution in avalanche terrain where the wind has drifted snow. The most likely places for wind slabs to develop are near ridgelines, convex rolls, and the base of cliffs, especially above treeline.  Use visual clues, like textured surfaces and "fat" looking drifts, to identify stiff wind slab locations. Stick to forested areas, sheltered from recent winds. Avalanches will be larger and easier to trigger above treeline.

    Thursday night into Friday you can expect another round of wind forming fresh slabs. Recent slabs drifted over various slick or weak snow surfaces.  Even in wind-sheltered terrain, you may still be able to trigger avalanches at the interface that was buried on the 3rd. You can use snow profiles to look for any weak layers that may have been buried at the beginning of the storm.

    (2/9/2023)

    An intentionally dropped cornice triggered this D2-sized avalanche on a leeward slope. Cashmere Mtn, E, 6,500ft 

    Photo: Matt Primomo

Avalanche Discussion

On Thursday, Matt Primomo found reactive conditions on leeward slopes of Cashmere Mountain. An intentionally dropped cornice triggered a D2-sized avalanche (see photo above) that ran on the new/old snow interface. A nearby observer reported a small skier-triggered avalanche in steep, sheltered terrain below treeline. 

Near the Cascade Crest, you can find almost 2 feet of recent snow that accumulated since February 3rd. Strong wind during the storm, followed by sun on Wednesday affected the surface snow. On Wednesday, observer reported loose wet avalanches on steep sunny slopes of rock Mountain near the western border of the zone. You may see more loose wet avalanches on sunny slopes on Friday. 

Earlier this week, Katie Warren went to the westernmost and easternmost edges of the East Central zone. Not surprisingly, snowpack conditions in these locations are quite different. A deeper and stronger snowpack exists in the western portion of the zone, and further east, a shallower snowpack with more prominent and concerning buried weak layers. Common landmarks in these snowpacks are the MLK crust and the Christmas Crust, buried .5-1.5ft deep and 3-4ft, respectively. The recent cold weather weakened the snow above and below the MLK crust into weak, faceted grains, creating a weak structure that we'll watch closely after this storm.

In the lower Little Wenatchee River Drainage, Katie found 300cm of snow at 5600ft that increased in strength with depth. Just outside of the Mission Ridge Ski area on Sunday, the height of snow was 230cm of snow, and while much of the snowpack was strong 1F or P rounded grains, two prominent layers of buried surface hoar exist. The lower layer of surface hoar, buried on January 4th, is still producing propagating test results, despite being below the MLK crust. We are still tracking this layer but don't anticipate avalanche activity on this layer during this storm. However, a layer of surface hoar, buried on January 18th, may produce avalanches with this new snow load. So keep it in your mind, and choose conservative terrain, if traveling in the Wenatchee Mountains. 

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