Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A potent storm will hit Snoqualmie Pass on Saturday night, resulting in dangerous avalanche conditions. By Sunday morning, rising temperatures could create a messy day with overlapping problems. Avalanches will be more likely on slopes over 35 degrees, whether they are wet or dry.

Avalanche problems

  • Storm Slabs

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

    Saturday night's storm should deliver roughly a foot of new snow, accompanied by wind and rising freezing levels. These are all common ingredients to create a storm slab problem.  Slabs should be larger and more sensitive as you ascend in elevation or in wind-loaded terrain. Use small test slopes or quick hand pits as you travel to determine how the new snow bonded to the old surface or if it is "upside-down" (heavy snow over weaker snow). Cracking of the surface or new avalanches are red flag signs of instability that you shouldn't ignore. You should avoid open slopes over 35 degrees until the snowpack has had time to adjust to the new load. 

    (1/4/2025)

    A shallow slab that occurred naturally on Mount Snoqualmie. This one is on a convexity and was likely wind-loaded. It may have been triggered by snow shedding from trees above.

    Expect slabs to be much larger on Sunday.

    Photo: Celia Harvey

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    As mentioned above, the storm is ending on a warming trend. Once temperatures bump up, expect rain to fall on the new snow at lower elevations, How much rain is tough to say, but the initial onset should be during the overnight hours. That means that peak instability for wet avalanches should be over by the time you step out of your car on Sunday morning. At that time, it won't be hard for you to tell if you need to consider these slides as you travel. If the snowpack is wet or it's still raining, be leery of slopes over 35 degrees or rocky ledges where wet avalanches are more likely. Don't let a small slide push you into a creek or hole where the consequences are higher. 

    Another hazard to consider with this warm-up are the tree bombs. They're huge right now! As temps rise, the wind blows, and rain potentially falls, these large chunks of ice and snow could fall. They're a hazard in their own right, but can also trigger avalanches on slopes below, similar to a cornice collapse. 

    (1/4/2025)

    Pinwheels and rollerballs are a sign that the snow is moist and wet avalanches are possible. These occurred as snow shed from a tree as temperatures increased.

    Photo: Andy Harrington

Avalanche Discussion

Saturday night should be the grand finale in our multi-week storm track which rapidly increased snowpack depth throughout the zone. During this period, The Pass has become "in" for backcountry recreation of all types. On Saturday, NWAC forecasters on Snow Lake Divide (4770') found roughly 10 feet of snow depth! Half of that was on top of the Solstice Crust, meaning we have doubled our snowpack in the last 2 weeks. By Sunday morning, expect another foot to have fallen at most elevations. Avalanche hazard may be highest first thing in the morning as the storm wraps up.

As alluded to above, the kicker will be that this storm will end warm, as many storms have this season. The timing is a little up in the air, but the peak warm-up is expected to occur after the bulk of precipitation ends. Hopefully, that will limit the rain's influence. Don't take that to the bank, however. Wherever you're recreating, take note of the weather and how the snow surface is changing as a result. Then determine if you have wet or dry avalanche problems to manage. You may have both. 

NWAC forecasters observed that the snowpack is generally well-settled and strong over the Solstice Crust. There are still easily identifiable interfaces, and one layer about 8 inches below the surface was continually highlighted with snowpack tests. It did not show signs of propagation, but in neighboring zones, a similar layer has been more troublesome. If you see avalanches breaking widely or wrapping terrain features, step your terrain choices way back. 

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