Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

7:30am Update: Increased the avalanche danger to HIGH at mid and upper elevations because we expect more precipitation, increasing the likelihood of large natural avalanches. 

Warming temperatures, rain, and high-elevation snow will make Saturday an unpleasant and dangerous day in the mountains. Smaller avalanches in new or wet snow could step down to deeply buried weak layers, resulting in very large and destructive avalanches. Choose lower-angle slopes and stay well out from under steep open slopes above. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–2.5

    If you're headed out into the mountain for a warm and wet day on Saturday, choose lower-angle terrain. Avoid traveling on or near large, steep terrain features. Give yourself large margins of safety from potential runout zones. One of these avalanches could run further and break wider than you may expect. 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. These avalanches could run as wet slabs at lower elevations, which may make them even more unpredictable.The snowpack is resting on a weak foundation. A layer of facets and decomposed crusts buried around the Solstice have continued to cause avalanches since early January. 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 is the area where you are most likely to trigger one of these persistent slabs. Further west, the weak structure is more deeply buried and may be more difficult to trigger. However, the warming temperatures and precipitation could be the tipping point, making these slides more likely in other areas of the zone. Since the weak layers are more deeply buried, an avalanche in these areas could be much larger, breaking 3-4ft deep. Cornice falls and smaller avalanches could also step down to these deeper layers. 

    (1/24/2024)

    Very large hard slab triggered with explosives at Mission Ridge.

    Photo: Mission Ridge Ski Patrol

  • Loose Wet

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

    Wet loose avalanches are possible at lower elevations as rain and warming temperatures break down thin surface crusts from the past few warm days. At mid-elevations, rain may fall on dry snow for the first time, and wet loose avalanches could run earlier in the day. Wet loose avalanches often start from trees, rocks, or cliffs shedding onto the slopes below. You can also trigger one that begins from your equipment, entraining snow and gaining speed as it moves downhill. Don't let one of these wet avalanches grab and drag you into or over terrain traps such as trees, gullies, or cliffs. Wet loose avalanches could be the first sign that larger, more unpredictable wet slabs are possible. Smaller avalanches that begin loose could trigger a much larger wet slab. If you start to see rollerballs or small, wet loose avalanches, your best option is to move to lower-angle slopes until this wet storm moves on from our mountains. 

    (1/4/2024)

    Rollerballs like this are the first sign of unstable wet snow.

    Photo: Katie Warren

  • Wind Slabs

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

    Upper elevations may escape most of the warming, at least for Saturday, and 5-8 inches of new snow with moderate winds could form stiff wind slabs on lee aspects. Steer around steep slopes where you find pillow-like drifts. Slopes below corniced ridgelines, the base of cliffs, and confined features are likely spots to trigger a wind slab. You can use small test slopes to gauge the reactivity of these fresh slabs. But keep in mind, while these avalanches might be small, there is a risk of them stepping down and triggering a larger persistent slab. 

    (1/20/2023) Small wind loaded rolls like in this photo are a good way to test the reactivity of new wind slabs. If they break into a mini avalanche, steer clear of larger steep slopes with wind drifts.

    Photo: Josh Hirshberg

Avalanche Discussion

Precipitation totals in the East Central on Friday night and Saturday may reach over 1" of water equivalent. Easterly flow may keep things cooler than the west slopes but expect an upward temperature trend. Saturday's freezing levels will likely top out around 5500ft, so you may find dry snow at the upper elevations. We are relatively confident that this weather pattern will induce another round of persistent slab avalanches in the Wenatchee Mountains. More uncertain is if this will be enough to activate the persistent weak layers lurking deeper in the snowpack throughout the rest of the zone. Build this uncertainty into your travel plans and choose conservative terrain, even in areas where we have not seen persistent slab avalanches yet. The dry snowpack is still in transition, and with multiple crusts and weak layers, we could see avalanche activity increase significantly in a short period. If you begin to see larger natural avalanches or any indications that smaller wet loose avalanches are initiating wet slabs, increase your margins further from avalanche terrain.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.An NWAC forecaster out near Blewett Pass on the 25th observed compression test failure on the Solstice Crust upon isolating the column. Other snowpack tests also indicated this layer had a propensity for propagation. They also experienced collapsing and observed a couple of small, natural wet slabs. The weak structure is widespread throughout the zone, although buried deeper and less reactive than in the Wenatchee Mountains. The critical thing to keep in mind is that as the snowpack experiences prolonged warming, other areas of the zone could begin to see increased reactivity and avalanches on these persistent weak layers. 

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

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