Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Recent avalanches are the greatest indication of instability - and we've had a lot of avalanches this week.  Wind slabs may be the "in your face" problem on Tuesday, but deep and deadly avalanches are what should be on your mind. Avoid big open terrain to help minimize your exposure to one of these ticking time bombs.

Avalanche problems

  • Wind Slabs

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

    There is plenty of evidence of the recent windy weather in the mountains right now. Textured surfaces, fresh cornices, large drifts, tree debris, and firm wind slabs litter the landscape. It's not a stretch to say that triggering a wind slab will still be possible on Tuesday. These may not be your standard wind slabs, however. There are likely plenty of hard slabs out there, which are notoriously difficult to assess for recreationalists and professionals alike. These slabs will be firm and may feel hollow. Your best bet will be to identify wind-loaded features and avoid them. Look for those visual clues and areas that look "fat" compared to the surrounding terrain near ridgelines, rocky outcrops, or on convex slopes. 

    (1/15/2024)

    Textured and firm surfaces, fresh cornices, and actively blowing snow. The nearest part of the cornice is starting to crack.

    Photo: Andy Harrington

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    This is the problem that should be shaping your travel plans.  We’ve been talking about weak layers in the snowpack for a while. These layers remain active in the zone as natural and explosive-triggered slides propagate widely and wrap terrain features. This isn’t a problem you can tiptoe around. We’ve found a poor snowpack structure everywhere we have dug a hole in recent weeks. The question mark is not about size or distribution but the sensitivity to triggering. Many of these avalanches failed with relatively small triggers, in some cases humans. It may take something bigger, such as a step-down, cornice, or explosives, as we move forward.  Maybe it will all fall apart on Wednesday when snow returns? These slides are erratic and scary. You will likely not see any red-flag signs of instability before one of these slabs fails. Slopes could contain multiple sets of tracks and then release without much rhyme or reason. You should consider staying off big open slopes where triggering an avalanche on this layer would result in a slide that would likely be unsurvivable. 

    (1/14/2024)

    A widely propagating slab on the SE side of Mount St. Helens was observed on Sunday.

Avalanche Discussion

On Monday, NWAC forecasters were out in the Crystal Mountain and White Pass areas. Reports from both locations near the crest were similar - cold wind, actively blowing snow, and plenty of wind-effect. In sheltered terrain, the surface has started to weaken. Over at Paradise, backcountry travelers noted plenty of wind effect, meaning those east winds extended far from the crest. Old (but sizeable) avalanche crowns were spotted at Paradise and Crystal—further documentation of our wild week.

Crystal Mountain Pro Patrol was out testing our deeper layers of concern, which resulted in another notable avalanche. That makes nine days in a row in which a notable (D2.5 or greater) avalanche has been reported in our zone. That's a lot of activity, especially considering the last few days have been generally benign weather. 

Hopefully, that helps drive home the point that these deeper layers of concern are not going away or settling out. If not, take a look at the photo of the avalanche on Mount St. Helens from Sunday (1/14). It's gigantic and spans a far distance. We're dealing with an issue not often found in the Pacific Northwest. Instead of these layers healing, they're actually degrading over time. As the slab above them thickens and snowfall returns on Wednesday on a slight warming trend, more slopes could reach their tipping point. Or maybe these layers will go to sleep and wait until later. That's the uncertainty we're dealing with.

The 12/30 and Solstice Crusts are 3-4 feet deep in most areas, with a mix of well-settled storm snow and wind slabs over them. Even at lower elevations, the snowpack structure is weak and showing signs of instability. 

As our next storm approaches, you could see a flurry or two before sunset, particularly down south. We're expecting snow Tuesday night with the brunt of the storm on Wednesday. Please keep submitting information about what you're seeing out there.

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