Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

It's a low likelihood, high consequence situation in the mountains right now. A large trigger like a cornice fall, snowmobile, or group of people in the wrong spot could trigger a very large and destructive avalanche on deeper weak layers. Stick to lower-angle and well-supported slopes, and give yourself a wide buffer from bigger terrain. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    Choose well-supported and lower-angle terrain. Identify large, steep terrain features and avoid them. Stop and regroup in safer areas, giving yourself wide safety buffers away from potential runout zones. A good strategy is patience and conservative terrain selection. If you experience whumphing collapses, use extra caution to avoid steep terrain. However, you may not get warning signs before triggering an avalanche.

    The snowpack is resting on a weak foundation. A layer of facets and decomposed crusts that were buried around the Solstice have continued to cause avalanches for a couple of weeks. Persistent slabs are a tricky problem, often leading to a false sense of security with no apparent signs of instability. This weak structure isn't limited to the Wenatchee Mountains, but it's where all the recently reported activity has taken place. Further west the weak structure is more deeply buried and may be more difficult to trigger. If you got unlucky, or a cornice fell, a 2-4ft deep avalanche could result. 

    (1/24/2024)

    Very large hard slab triggered with explosives at Mission Ridge.

    Photo: Mission Ridge Ski Patrol

Avalanche Discussion

Since Wednesday, the mountains picked up anywhere from 5-8" of new snow. With the recent warming, you're likely to find a couple of thin crusts in the upper snowpack. These top a hefty couple of feet of storm snow from the month of January. With the new snow comes the potential for small sluffs. These loose dry slides could run off steep cliffy areas during periods of heavier snowfall rates and could be triggered on steep slopes. Later in the day, at lower elevations or in the sun, look for rollerballs and feel for moistening snow as a clue to potential wet loose slides. At upper elevations, light winds could drift the new snow into small wind slab pockets. Look for slightly textured surfaces and cracking as a sign of these near ridgetops.

The Solstice Crust/Facet Complex in the Wenatchee Mountains has been active since late December and has continued to produce avalanches. Mission Ridge Ski Patrol triggered some very large (D2.5-D3), hard slab avalanches on Wednesday and Thursday with large explosive work. These were from north and east-facing slopes below corniced ridgeline in the upper 6,000ft range. Human-triggered avalanches on this persistent weak layer have occurred on Jan 6th, 12th, 15th, 19th, and 20th. While these avalanches have primarily occurred in wind-loaded terrain, we can't rule out avalanches in sheltered areas as there is a lot of storm snow above this layer.

NWAC forecasters were out on the 22nd and 21st in the far western edge and the eastern edge of the zone. Although the snowpacks ranged in depth from 150cm in the upper Icicle to only 100cm in the Blewett Pass area, there were certain commonalities that are worth discussing. First, there has been a substantial amount of new snow since early January (2-3ft). Second, we could identify a weak structure near the base of the snowpack that consisted of faceted grains over and often beneath a weak, decomposed crust (2-3ft down). Third, snowpack tests showed the potential for avalanches to propagate on this layer in both locations.

If you get out, let us know what you see by submitting a public observation!

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