Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

On Sunday, an atmospheric river will result in very dangerous avalanche conditions throughout the West South zone. Natural avalanches large enough to travel toward lower elevations or break trees are expected. Traveling anywhere an avalanche can start, run, or stop is not recommended.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    Soaking rain, strong winds, and warm temperatures will overload our predominantly cold and dry snowpack, resulting in large and potentially destructive avalanches. As rain starts to fall, you will initially see wet loose avalanches release. As water reaches any one of the numerous interfaces in the upper snowpack, expect larger and more dangerous wet slabs to begin to fail. Along ridgelines, sensitive cornices formed during our recent windy storms will start to sag and collapse. You may even see a few glides on rocky ledges. Needless to say, there will be a multitude of wet avalanche problems on Sunday, and they're all impossible to predict or manage. Don't try to outsmart this one or cut it close. Travel in avalanche terrain is not recommended. 

    (3/22/2025)

    A very large slab avalanche that released naturally in the Tatoosh Range on Saturday. Similar-sized slabs may be widespread once rain and extreme winds impact the zone on Sunday.

    Photo: Tim Hardin

Avalanche Discussion

It's going to be a messy Sunday around the West South zone. An atmospheric river is set to drench our upper snowpack in most locations, resulting in widespread natural avalanche activity. This storm will end our cold and snowy March, which resulted in several feet of storm snow. In fact, the West South zone could be considered the snowiest in the NWAC network, with all major weather stations reading over 100 inches of snow. At Chinook Pass, we came up just short of 200 inches! 

All that March storm snow is currently cold and layered, sitting over a crust formed during our last atmospheric river. We've had a steady stream of avalanche activity all month as the mountains adjusted to each storm. On Saturday, very large slab avalanches occurred naturally in the Tatoosh Range. Our friends at the USGS have sent along information that large to very large avalanches have been occurring for a few days on Mount St. Helens and Mount Hood. A glance at the neighboring Mt. Hood forecast can help you visualize the types of slabs we're talking about.

This process will only continue over the next 24-48 hours, with several rounds of natural avalanches expected. With our current snowpack structure, wet slides have the potential to descend long distances or break trees. Because of this, you won't want to try to sneak around at lower elevations or other "safe" forested areas. We're talking about unsurvivable wet slides here. Again, travel in avalanche terrain is not recommended on Sunday. This means you should avoid anywhere an avalanche can start, run, or stop.

Of course, our large zone is not without variability. There are a few outliers, such as Crystal Mountain, where the deluge may not be quite as intense. And yes, there will be snow overnight and possibly the morning before freezing levels rise above the tops of the peaks. On the volcanoes, you may be able to get above the rain and find dry snow being whipped around by strong to extreme winds. All of those are true and make the forecast a bit nuanced. But they're not the main story. If it's raining outside, don't travel in the mountains. There will be avalanches.

Regions covered