Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Deep storm snow and wind have left heightened avalanche danger on slopes 35 degrees and steeper. You can still trigger large and surprising avalanches, especially in the eastern and western parts of the zone and where wind has stiffened snow surfaces. Loose avalanches or sluffs may run easily on steep slopes outside of wind affected terrain. 

Avalanche problems

  • Loose Dry

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

    On wind-sheltered slopes, the snow surface is light and uncohesive. You can trigger loose avalanches on slopes near to 40 degrees. While these avalanches can be easy to predict, they can be dangerous if you get caught off guard. Use caution around terrain traps like rocks, cliffs, and gullies where loose avalanches could bury you or cause injury. While traveling on steeper slopes, be aware of any snow that begins to slide around or behind you. Slow down or move to the side so these avalanches don't carry you down-slope. Make sure to stop and regroup well off to the side and in safer terrain if others are traveling on overhead slopes.

    (2/9/2021) An example of dry loose avalanches on Snoqualmie Pass. Don't get knocked off your feet or pushed into a terrain trap by one of these when there is so much snow. [Photo: Zack Wentz]

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    You may still be able to trigger wide and surprising avalanches on older, faceted grains or buried surface hoar. Audible whumphing collapses, cracks shooting through the snow, and widely propagating avalanches are all warning signs. You could trigger slides on convex rolls and unsupported features, especially areas that have been recently stiffened by wind. While the likelihood of these avalanches is dropping through time and quieter weather, the consequences remain high. If in doubt, opt for lower angle terrain and consider sticking to slopes less than 35 degrees.

    Persistent slabs have not been a uniform, widespread problem in the zone, although sporadic avalanches on a variety of weak layers have left us with a tricky pattern to decipher. Heres what we do know: Observers suspect a very large avalanche involved persistent weak layers near Rainy Pass on the 8th (see discussion). Layers of buried surface hoar can still be found in the top 3 ft of the snowpack near Washington Pass. East of Washington Pass, the most recent known persistent slab avalanche was on February 3rd. Far east and just west of Washington Pass, you may be able to trigger avalanches on older, weak facets above or between crusts from mid-January. This weak layer is also about 3 feet below the surface in these areas.

    (2/9/2021) A very large avalanche at 6,400ft, ENE near Rainy Pass. This avalanche may have run on 8th on a deeply buried persistent weak layer. You can see many snowmobile tracks in the area. Photo: Jeff Ward

Avalanche Discussion

An avalanche fatality occurred on February 8th in the Knox Creek drainage in the neighboring East Central zone (See the short video in the media gallery below). Our condolences go to the friends and family of those involved. Similar avalanche conditions may exist near the eastern and western boundaries of this zone.

On February 9th, an observer on Whistler Mountain reported sudden and propagating test results on a west aspect at 6,000ft as well as on a NW aspect at 6,600ft. The weak layer was facets on a crust from mid-January (1/14) down about 90cm at 6,600ft. This weak layer appears to be more shallowly buried and more problematic west of Washington Pass, as well as in the far eastern mountains of the Twisp River and Chewuch drainages. A very large avalanche was reported at 6,400ft, ENE near Rainy Pass. This avalanche may have run on the 8th, perhaps on the same (1/14) persistent weak layer as observed on Whistler Mtn.

On February 8th, observers near the hairpin on Washington Pass reported an additional 5 inches of snow overnight with over 2 feet of storm snow since the 5th and wind transport at ridgetops. Observers on Delancey Ridge reported about half as much storm snow and still found tests indicating propagation on the Jan 30th interface of facets and surface hoar at 6050ft on a southeast aspect. On Sunday, observers dug a profile on a SW aspect at 7,200ft and found reactive storm interfaces down 1 foot and a layer of rounding facets (likely Jan 30th) about 2 feet below the surface. 

On Saturday, a skier intentionally triggered a small wind slab on a cross-loaded southwest slope at 7400ft near Washington Pass. On February 3rd, we believe that a significant portion of Portley Bowl avalanched naturally following a ski triggered slab on a smaller part of the bowl on the 2nd. Another skier had a close call, also on February 2nd. We suspect buried surface hoar as the culprit for these two avalanches last week.

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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