Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The recent storm parade will leave behind overlapping avalanche problems to manage on Wednesday at Snoqualmie Pass. Don’t expect the snowpack to stay stagnant this time of year - new snow problems can quickly transition to wet problems given the right weather inputs. Make travel plans that give you plenty of options to adjust to changing conditions and avoid overhead hazards.

Avalanche problems

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–2.5

    Large and unpredictable shedding avalanches such as Glides should be the avalanche problem that shapes your travel plans on Wednesday. These difficult-to-forecast events can fail without warning, sometimes long after the rain has stopped. On Wednesday, sun breaks and an end to our multiday storm cycle could provide the needed boost to tip the scales for some of these beasts. Don’t linger on slopes where you see crevasse-like cracks or hanging blocks of snow on rocky ledges. 

    You could see other wet avalanches as a result of solar input on Wednesday. A new round of Loose slides could occur if the sun is able to destabilize the newly fallen snow. Although they may start small, they have the ability to entrain snow and grow large as they descend, sometimes triggering slabs in the process. Be leery of steep slopes in the sunshine if you are sinking into wet or moist snow past your ankle or see new fan-shaped avalanche debris/rollerballs.

    (4/11/2023)

    A frequent Glide slope near Alpental Ski Area known as Shot 8 had plenty of debris and some cracks, but has not yet fully released its wintertime snowpack.

    Photo: Andy Harrington

  • Wind Slabs

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

    At upper elevations, Tuesday’s snowfall could have drifted into thicker pockets near ridgelines, rocky features, or convex rollovers. Look for textured surfaces or areas that look “fat” compared to the surrounding terrain to identify wind-loaded features where triggering a small avalanche is more likely. In isolated locations, they could entrain moist snow from below and start to increase in size. Use test slopes and hand-pits as you travel to check the bond to the old snow surface and how easily the new snow may be failing due to your weight. If the snow is failing easily in your tests, start thinking about the possibility of triggering slabs on unsupported convex slopes away from wind-effected terrain.

    (4/11/2023)

    A skier-triggered slab in the new storm snow on 4/11. [N 5000']

    Photo: Public Observation

Avalanche Discussion

Upper elevations around Snoqualmie Pass picked up anywhere from 7-9 inches of new snow on Tuesday, with considerably less down low. NWAC forecasters in the Alpental Valley found that the new snow was poorly bonded to the underlying surface and that small slabs were easy to trigger with ski cuts on test slopes. Water had percolated into the snowpack roughly 2 feet below the surface at 4600 feet and numerous recent avalanches were noted. Most viewed slides had failed near rocky terrain and not surprisingly, were wet in nature. Upper elevations were not observed due to poor visibility, but word is that the sun made an appearance later in the day.

Our snowpack has been through a lot in recent days as springtime weather has impacted the zone. Over 2 inches of precipitation (SWE) has fallen since Saturday afternoon, most of which was rain, and drastically changed the landscape. Although it is undoubtedly Spring out there, we’re still in a state of transition away from our wintertime snowpack. Under the surface, cold layered snow still exists and this week should be unseasonably cold for April. You’ll likely encounter periods of sunshine, snow showers, and rain all in the same day as you travel through the mountains which can lead to a myriad of avalanche conditions for you to unpack.

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