Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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

The first wave of a multi-day atmospheric river will result in dangerous avalanche conditions on Saturday. If you're heading out, be sure you are back at the car early to avoid the brunt of the storm Saturday afternoon. As that next round arrives, avalanche hazard will increase rapidly, and travel in the mountains is not recommended.

Avalanche problems

  • Wet Slabs

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

    Precipitation on Friday night should diminish by the morning hours before the main event brings soaking rain on Saturday afternoon. You'll likely encounter lingering wet issues below Friday night's rain/snow line, such as rollerballs, pinwheels, wet loose, and some slabs. There may not be enough liquid water moving through the snowpack to set off our persistent weak layers and drive High avalanche danger in the morning.

    But as freezing levels rise and the main storm hits later in the day - watch out! Larger and more destructive natural avalanches will start to fail, resulting in very dangerous avalanche conditions. The surface snow will start shedding; then, we'll peel the snowpack onion back layer by layer. All those persistent weak layers we've been forecasting for a month, The January Drought Layer (JDL), the 1/10 complex, and the 2/13 interface, will all be potential failure points at some point this weekend.  Don't thread the needle - avoid anywhere an avalanche can start, run, or stop.

    (2/18/2025)

    This very large natural avalanche released Tuesday afternoon. on the backside of Chair Peak. 

    Expect numerous avalanches this size over the weekend.

    Photo: Zack Novak

  • Storm Slabs

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

    On Friday night, heavy snow, warming temperatures, and moderate to strong winds should combine to create sensitive slabs above the rain/snow line. If you work through the wet lower elevations seeking dryer snow, be leery of slopes over 35 degrees where triggering an avalanche is more likely. Shooting cracks, blocks of snow failing in your tests, or new avalanches are all signs that the snowpack is unhappy, and you should head for lower-angled terrain. If you are playing in the snow at upper elevations, be sure you are well on your way to the car by the time the rain hits in the afternoon because conditions will get incredibly dangerous quickly at these elevations.

    (2/18/2025)

    A natural storm slab triggered by a small loose avalanche.  

    Similar slides could occur on Saturday at upper elevations.

    Photo: Trevor Kostanich

Avalanche Discussion

A multi-day atmospheric river event will impact the zone throughout the weekend. The first round on Friday night should bring rain into the middle elevation band and heavy wet snow above, creating a two-elevation band type of forecast for the bulk of Saturday. However, on Saturday afternoon/evening, the real storm strikes as freezing levels skyrocket and an atmospheric river deluge impacts the zone. Extremely dangerous avalanche conditions are expected to develop on Saturday night, so it's not the time for that camping trip you've been planning. Expect rain at all elevations by the time the sun sets on Saturday. It may start up as early as roughly 3:00 pm. So give yourself plenty of time to ensure you return to your car early and avoid the most dangerous conditions. Once the main event starts, traveling anywhere an avalanche can start, run, or stop is not recommended. An avalanche warning will be in effect on Sunday, and the weather driving it begins on Saturday afternoon.

If you've skimmed the forecast at any point over the last month, you'll have noticed us talking about persistent weak layers throughout the zone (the JDL, 1/10 complex, and 2/13 interface). You may have noted we aren't forecasting a persistent slab problem for Saturday. Those layers are still in place and are a significant concern heading into the rain. We transitioned the problem to Wet Slab for the upcoming downpour. Expect cornices, upper layers in the snowpack, and eventually older layers to fail over the weekend as several rounds of avalanches occur. Some may run full path from mountainsides far above you toward valley bottoms or into the trees.

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