Lawinenlagebericht

East Slopes Central

Northwest Avalanche Center
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Lawinengefahr

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

Close to a foot of new snow fell on Thursday in the southern portion of the zone. You could trigger widely fracturing slabs in wind drifted areas, and on slopes that receive direct sun. Loose slides may run naturally and could be triggered on steep slopes in the sun. With all of these overlapping hazards, choose simple and well supported terrain while the new snow settles out.

Lawinenprobleme

  • Wind Slabs

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

    You'll find deep drifts as you gain elevation, especially in the Wenatchee Mountains, Salmon la Sac, Teanaway, and Icicle. These slabs are likely to be resting over weak, faceted surfaces or the slick Early February Crust (EFC). To avoid triggering an avalanche, stick to lower angle and well supported slopes at mid and upper elevations. You can expect to find  slabs below corniced ridges, convex rolls, steep gullies, and at the base of cliffs. Look and feel for pillow-like drifts and similar wind textured surfaces to clue you into this potential. Its mid February, and the suns stronger rays may create cohesive slabs even outside of wind drifted areas. This is a somewhat unique setup where you might be able to trigger slab avalanches on south facing slopes by mid day because of this. On Tuesday, skiers in the Icicle Creek area triggered a small wind slab that failed on weak, faceted snow over the EFC. While this avalanche was small, it may be a sign that we could begin to see large or surprising avalanches failing on persistent weak layers with this additional snow load.

    (2/13/2024)

    Skier triggered wind slab on the early February Crust on a NE aspect at 6,500ft in adjacent Stevens Pass on Tuesday.

  • Loose Dry

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

    With the low density new snow, sluffs may run naturally with direct sun, or could be triggered by a person on a steep slope. These shouldn't pack too much punch, but the larger the terrain feature the more destructive they could become. Look for other point releases, and feel for moistening snow surfaces on steep south facing slopes. Avoid hanging out beneath large steep or cliffy features during the 'heat of the day' while the new snow settles out.

    A natural solar triggered loose dry avalanche from a previous season. Photo: Josh Hirshberg

Avalanche Discussion

The Wenatchee Mountains picked up 10" of new snow, and observers reported areas of about 16" higher on Blewett Pass with a fair amount of wind affect. Mission Ridge reported triggering shallow (5-8" deep) slabs that ran on the old/new interface with control work. Forecasters were out on Blewett Pass, and found wind drifted areas to produce shooting cracks readily when provoked. She also got one collapse, and the culprit was a thin layer of faceted grains above the crust from early February.

Expect mostly sunny skies on Friday, with a thin layer of high clouds that could dampen the sunshine by afternoon from south to north. Temperatures remain cold in the shade, but the mid February sun is growing stronger so it should start to affect snow surfaces more substantially. 

Prior to this last storm, two skier-triggered avalanches failed on weak, faceted snow over the EFC: A small avalanche in the Icicle Creek area and a slightly larger avalanche on Jim Hill in the Stevens Pass zone. These could be the first signs to expect avalanches on this weak snowpack setup in the future. Observers have been finding buried layers of faceted snow above the stout crust from early February (EFC). On Tuesday, NWAC Forecasters traveled into the Mission Ridge area and found 6-8 inches above the EFC. They also reported reactive wind slabs failing on small surface hoar and facets above the crust. These slabs stayed small (< 1 ft) but were sensitive to triggers due to these weak grains. Other observers also found surface hoar over the early February crust last Tuesday at Blewett Pass. These variable observations and widespread weak surfaces could result in 'hit or miss' instabilities now that theres an additional snow load. Consider making conservative decisions for the next couple days, to give the snowpack time to adjust.

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