Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
View on map

Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map
Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous avalanche conditions should persist on Friday as more winter weather rolls through Snoqualmie Pass. Look for recent avalanches or cracking of the snow surface as indications that the snowpack is unhappy and you should avoid slopes over 35 degrees. Some avalanches could break in surprising ways by failing above you or wrapping around terrain features.

Avalanche problems

  • Wind Slabs

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

    You’ll likely need to manage Wind Slabs on Friday near ridgelines, the base of cliffs, confined chutes, or on convex slopes over 35 degrees. These slabs should be larger and more reactive as you ascend in elevation. Fresh cornices that look sharp, textured surfaces, or new drifts behind objects are visual clues you can use to determine wind-loaded aspects. Once you know which way the wind was blowing, look for smooth “pillow-like” piles of snow that appear “fat” or feel stiffer compared to the surrounding snow to identify Wind Slabs. Using small test slopes or uptrack tests as you travel can give you clues about how wind-drifted snow is reacting to your weight as a traveler. If you suspect a slope to be wind-loaded, best to avoid it at this time.

    In wind-sheltered areas, there’s still a chance you could encounter reactive slabs on slopes over 35 degrees. Use your test slopes and uptrack tests to look for cracking and failing of the snow as mentioned above. Additionally, you can use small hand pits as you travel to look for failure points in the recent storm snow. If you find that snow is cracking or failing easily in blocks during your tests, avoid slopes over 35 degrees.

Avalanche Discussion

Wind and precipitation should continue on Friday at Snoqualmie Pass, but intensities will likely be a notch lower than what was experienced on Thursday. As of Thursday afternoon, the Pass Proper has picked up somewhere between 5-8 inches of snow with wind gusts as high as 60 mph. 

Observations from Thursday are a bit limited, but Alpental Pro Patrol reported isolated Wind Slabs up to 1 foot deep during their morning mitigation efforts. On the eastern part of the zone, backcountry travelers near Cottonwood Lake reported similar depths as well as plenty of graupel mixed into the storm snow. They also reported seeing cornices fail naturally.

Prior to the storm widespread weak surface hoar was reported and a thin sun crust was expected to have formed on Wednesday afternoon on slopes that see direct sunshine. These prior surfaces could mean a poor bond has formed at the new/old interface and could result in some surprising avalanches breaking above you or spanning far distances. Combined with fluctuating freezing levels, strong winds, the reported graupel, and a less than steller bond even deeper in the snowpack at the 2/25 interface - there are numerous potential points of failure in the upper snowpack that you should investigate before committing to a slope. You should also be aware of freshly formed cornices, they will likely be sensitive and could fail easily.

Regions covered