Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Wind-loading from a variety of directions and E flow on Sunday will maintain heightened avalanche conditions near and above treeline. You are most likely to trigger an avalanche on wind-loaded rollovers steeper than 35 degrees with wind-loaded slopes existing well below ridgelines and in some cases into the near treeline band. Active snow transport, fresh wind lips, and firm or punchy snow layering are all signs to mellow your terrain selection.

Avalanche problems

  • Wind Slabs

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

    Maintain vigilance on Sunday as you could trigger a widely propagating Wind Slab avalanche that will be large if it runs down to weaker snow on top of the crust. Shifting winds (SE to SW and back to SE) will continue to create unusual loading patterns with light amounts of new snow transported by the moderate winds and very strong gusts. These slabs may be found well near to, but also well below ridgeline, and along the sides of mid-slope features. Slabs will form atop previously wind-affected surfaces, smooth ice, or weak soft snow that rests atop the crust. Slabs sitting over weak soft snow sitting on a crust are likely to maintain reactivity longer and propagate more widely. Unfortunately, it is difficult to predict where you will find them. Use visual clues such as cornices and wind lips to help you identify recent wind loading patterns. Anticipate which aspects and features could hold wind slabs. Steer around steep open and convex slopes if you suspect wind loading. You may find larger and more dangerous avalanches at higher elevations and later in the day. 

    In more sheltered areas, a cooling trend has created a right-side-up snowpack structure and you may see loose dry avalanches. These could run quickly on steep terrain features if they occur over the icy crust.

    (12/23/2020) Blowing snow from moderate southeasterly winds was forming thin new wind slabs. Chair Peak, 5200' N aspect.

Avalanche Discussion

We're expecting increasing chances for sunshine as the day wears on.  When the sun does appear, pay attention to rollerball activity and adjust your aspect before Wet Loose avalanches release from steep, southerly slopes.

Over 14" of snow now sits above a very prominent icy crust (12/21) formed during last weekend’s rain events with significant variations in depth due to wind loading. The icy crust should limit any avalanche activity to the snow above. Windy conditions prior to Friday night's storm created a variety of snow surfaces including soft weak snow, wind-scoured ice, breakable crust, and firm wind drifts. You may experience the weekend's reacting differently depending on which surfaces it accumulates on. In places where the icy layer is exposed or near the surface, a simple slip could easily turn into an uncontrolled fall. Use caution if you travel over these slippery slopes. 

At lower elevations, early season conditions still exist with numerous obstacles, open creeks, and holes in the snowpack. Give yourself extra time to deal with these hazards. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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