Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Our tropical temperatures may peak on Sunday, creating very dangerous avalanche conditions. Large, destructive wet avalanches may run naturally, or you could trigger them on steep slopes. Avoid traveling on steep terrain at mid and upper elevations. Be knowledgeable of the terrain above you, as avalanches may travel through elevation bands to valley bottom.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–2.5

    Plenty of recent snow overlaying a weak snowpack structure is a perfect setup for large wet slabs. Wet slab avalanches become increasingly likely with warm overnight temperatures like we expect on Saturday night. We expect daytime temperatures on Sunday to be even warmer and avalanches to become very likely. On Saturday, snowmobilers triggered a few large wet slabs on southerly and northerly aspects. These wet avalanches could be 2-4 ft deep and break surprisingly wide. You could trigger these massive slides or they could release on their own. The timing of wet avalanches is extremely hard to nail down, but we expect Sunday to be more dangerous than Saturday. How do we manage this problem? Avoidance is the only reliable strategy. Stay out of harm's way by avoiding travel on and under all large slopes greater than 30 degrees, especially during the heat of the day. Lower elevations may see avalanches run from above. So, know the terrain above you and avoid lingering in and near steep drainages that can channel sliding snow from above. Wet loose avalanches will also be widespread on Sunday. While these may be smaller and more predictable, they are an excellent trigger for wet slabs. The heat and sunshine will weaken cornices. Give these overhanging chunks some space. They could trigger wet loose or slab avalanches.

    (3/16/2024)

    Snowmobilers triggered this avalanche on a southern aspect in the Ahtanum on Saturday, March 16th. It likely failed and ran on the Early February Crust. 

Avalanche Discussion

The shed cycle continues across the East South mountains. A close call on Saturday, where snowmobilers triggered an avalanche in Ahutanum that failed on these deeply buried weak layers, is an indication of things to come as we continue to warm the snowpack. Sunday may be the warmest temperatures yet and might be the most dangerous day in the mountains during this summer time weather. Before this warm-up, we had a persistent slab problem present. There was a fatality two weeks ago in Ahtanum meadows, and in the neighboring East Central, we saw multiple large human-triggered persistent slab releases last week. This prolonged warm-up is an excellent reason to dial back your terrain selection. Instead, seek out sunny ridgelines or flat meadows far away from large avalanche paths.  

As with any warming event, there is a high level of uncertainty as to where, when, or even if this scale of avalanche activity will occur. On the other hand, big natural avalanches should not be taken lightly. It's worth noting that smaller wet loose, cornice falls, or snow shedding from cliffs can provide the trigger needed to pull out a very large avalanche. When planning your routes, consider that this is one of the times when an 'unexpected' avalanche might occur.

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