Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A winter storm will bring dangerous avalanche conditions across the East South Mountains. Avalanches may trigger easily and break widely if they fail on weak snow above a crust 1-3 ft below the snow surface. This stormy pattern will be a good reason to keep your terrain selection simple and stick to sheltered slopes below 30 degrees. 

Avalanche problems

  • Storm Slabs

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

    New snow will stack up during the evening hours, likely creating instabilities within the new snow. It will also create thick, reactive slabs in wind-loaded terrain. The heaviest precipitation rates will come during the early morning hours, so you may find the most reactive conditions during the first half of the day. These avalanches could break within the storm snow, at the old snow interface, or even deeper on a number of weaker layers. The new snow has recently buried a layer of facets and surface hoar. As such, slides may fracture widely and could be triggered from adjacent slopes. Above 5,000ft slides could run on more deeply buried weak layers, including weak snow and a crust from early February, so slabs could break over 2.5ft deep in places.

    Constantly assess the reactivity of the new snow while you travel. Be looking for blowing snow, shooting cracks, or snow sliding easily under your sled or feet. With a complicated snowpack with multiple weak layers present, consider sticking to slopes less than 30 degrees until this storm has run its course. 

    (2/22/2024)

    You could trigger similar avalanches on Monday.

    The crown of a skier triggered avalanche, size D2, 4"-1.5' deep. It was triggered from below on a 30-degree terrain, and ran on facets above the early February crust. Longs Pass, W, 6,200ft

Avalanche Discussion

The East South mountains will join the storm party Sunday night into Monday. As usual, we're looking at a wide range of precipitation totals across the zone. The western edges are forecast to receive over 1 inch of SWE, while you'll find less further east. Regardless of location, the new snow will fall on a cooling trend and should improve travel conditions significantly. It will also start testing weak layers in the upper snowpack. Beyond slab avalanches, keep loose snow avalanches in mind as well, especially if the sun pokes out. 

Just to the north in the East Central zone,a group traveling in the Teanaway drainage triggered a slab avalanche on a layer of facets just above the early February crust. The large (D2) avalanche occurred near Longs Pass, 6,200ft, W was triggered from a lower-angle, 30-degree slope near a cluster of trees. A crack propagated uphill and across in both directions. The avalanche ran to either side of the lower-angle feature and didn't involve the party that triggered it. You can check out their full observation here. This close call may be a sight of things to come.

Since February 14th, storms have brought 14-16 inches of snow to the East South zone. In much of the region, this new snow now sits over persistent weak layers of faceted snow over the slick Early February Crust (EFC). Observers in many areas of the Cascades, including in an NWAC forecaster in the Darland Mt area last week, have found weak, faceted snow just above the stout EFC crust and also over a thin, breakable crust buried on 2/14 on southerly aspects. This persistent weak layer has produced avalanches in neighboring zones (observation here). Since February 15th, 13 unintentionally human-triggered avalanches have failed on or just above the EFC throughout the Washington Cascades. We have reports of avalanches on all aspects between 5000ft and 8000ft. It has been a number of days since the last reported avalanche, but these problems can be tricky and linger in certain spots like steep, rocky terrain with a shallower snowpack.  

Expect a very thin snowpack at lower elevations and on some steep southerly slopes. Slick crusts, exposed obstacles, open creeks, and bare ground continue to make travel more adventurous. 

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