Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

The new storm snow is healing slower than usual at mid and upper elevations. Although chances are declining, you could still trigger a dangerous slab avalanche on large steep slopes near the crest. Sun and warm daytime temperatures may add to the mix by creating wet loose slides on slopes that catch the sun. Limit your exposure to steep slopes with potential grave consequences of a slab.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Warming temperatures and sun are expected to moisten snow surfaces on slopes just south of east through west. If you see rollerballs or moist snow surfaces, consider moving to lower-angled or more shaded terrain. Wet avalanches could come down from steep slopes, and you could trigger loose slides on them. Look for clues like rollerballs, and fresh fan shaped slides during the day. 

    (2/10/2023)

    Loose wet avalanches in steep, rocky terrain just west of Skyline rd.

    Photo: Matt Primomo

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    The new snow is having a slower time bonding to older, weak snow surfaces. The most likely place to trigger a large slab avalanche are high elevation, steep terrain and perhaps near rock outcrops. Other likely locations are on slopes with large cornices that loom over them. Cornices themselves may be easy to trigger. You don't necessarily need a heavily wind loaded slope for an avalanche though. Steep and unsupported slopes outside of wind affected terrain could be reactive.

    We're at the point when you may not get direct signs of instability before triggering a slide, but if you did it could be surprising and quite wide. While you could probably travel on many slopes and not trigger avalanches, keep this in mind and do your best to not get surprised or worse. Use well supported terrain, limit your exposure and make sure to use safe travel techniques.

    (2/9/2023) View to the north. E at 6,500ft. Photo: Matt Primomo

Avalanche Discussion

We have minimal new information from Friday. On Thursday the new snow was still quite reactive in the upper Icicle drainage, with multiple ski triggered slides reported. These were on north to southeast facing terrain at and above 6,000ft. Some were in open areas in the trees, not just heavily wind affected slopes. Observers also reported whumphing collapses on wind affected ridgelines in the Teanaway that day. The culprit for the recent activity has been the old/new snow interface, which often consists of small grained faceted snow and is about 1-1.5 feet deep. Strong westerly winds substantially built cornices in places they were otherwise not very impressive before this storm.

Common landmarks deeper in the snowpack are the MLK crust and the Christmas Crust, buried 1.5-2.5 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're still watching. On Stevens Pass, ski area control work and a few natural avalanches ran down to the MLK crust on the 8th.

In the eastern Wenatchee Mountains, 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. A layer of surface hoar, buried on January 18th may produce avalanches with the newer snow load on top. So keep it in your mind, and choose conservative terrain if traveling in the Wenatchee Mountains. 

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