Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Though the storm may begin to taper, dangerous and unpredictable avalanche conditions will continue on Monday. Destructive and deadly natural avalanches remain a possibility at all elevations. Steer clear of steep open slopes, and if you have to cross beneath an avalanche path, do so quickly and one at a time. If you head out, expect soggy, difficult travel.

Avalanche problems

  • Wet Slabs

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

    The full menu of wet avalanche problems—wet slabs, wet loose, and glide—remains on the table Monday. Even if the spigot from the sky slows or shuts off, liquid water will continue working its way through the snowpack, testing its strength and stability as it percolates and pools. 

    Wet avalanches, especially wet and glide slabs, are notoriously hard to predict. While the frequency of avalanches may have already peaked by the time you head into the mountains, the size may not have. Even if you don't observe signs of previous large avalanche activity, a destructive slide could release on its own and without warning. Avalanches could originate at any elevation, and with so much recent snow stacked over the late February AR crust, some slides could run thousands of feet, breaking trees as they charge into valley bottoms. Even wet loose avalanches that start out small could gouge deeply into the snowpack and grow plenty large enough to bury a human as they descend.

    Due to the combination of consequence and unpredictability, the avalanche conditions on Monday won't be "manageable". Consider avoiding any path or runout, and if you must cross a path, do so by moving quickly and with a purpose. Given the truly horrendous travel conditions on offer on Monday, the best option is to give the mountains some time. 

    (3/6/2025)

    This very large wet avalanche likely ran during the atmospheric river at the end of February. These types of avalanches can leave deep and heavy debris piles and run into low-angle terrain in the valley bottom.

    Photo: Dallas Glass

Avalanche Discussion

Though we have limited observations from the backcountry, the theme throughout the zone is rain and warm temperatures. Some areas received snow through Sunday morning before the switch to rain midday, and precipitation totals vary widely depending on location. Regardless, rain-on-snow=avalanches. We expect the rain to reach the highest elevation bands overnight into Monday. This equation should be on your mind no matter what you see in the mountains. 

Water takes time to percolate through the snowpack and there are many interfaces above the late February AR Crust where it could pool, destabilize the snow, and trigger an avalanche. In many parts of the zone, that process is only just beginning as of Sunday afternoon. Crystal Pro Patrol reports water percolation only down a few inches thus far, meanwhile, a wet loose avalanche crossed the road at Paradise and left a deep, though narrow pile of debris in its wake. In addition, a few small cornices broke and triggered shallow slabs in the Crystal Backcountry. We suspect a more widespread cycle may occur this evening and overnight. The timing of avalanches will play out differently depending on the previous snowpack structure and the quantity and rate of liquid water introduced into the snowpack. Once the water is in there, it is really challenging to know what it will do and how the snowpack will respond. What we do know is that it can take time, and this process will not have run its full course by Monday. Don't let an absence of prior avalanche activity lull you into thinking that a large avalanche couldn't release. This problem will be with us in some form or fashion until colder temperatures return.

Conditions will likely be more dangerous on the volcanoes, where more precipitation is falling than in other parts of the zone. If you venture into the highest terrain, you may find wind slab instabilities in snow that hasn't been rained on.

All in all, the message right now is simple: Monday isn't the day to try and outsmart this problem. 

Regions covered