Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

As you climb in elevation, watch for freshly drifting snow on Friday.   Steer around areas of stiffer, wind affected snow and watch for cracking in the surface snow.  Avoid open slopes steeper than 35 degrees where you could trigger a wind slab avalanche.   

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Increasing winds will start to transport new and recent snow on Friday.  Near and above treeline,  watch for drifting and stiffer, wind-affected snow as indicators wind slabs may be present. Use caution on leeward wind-loaded slopes over 35 degrees. On any slope, you can use quick snow pits and small, inconsequential test slopes to check if the snow slides easily. Look for a potential poor bond at the new/old snow interface where observers have reported weak surfaces, including surface hoar below 6,000ft.  Use caution in and around terrain traps, where avalanches could have serious consequences.

     

    (12/28/2020) Shallow skier triggered Wind Slab on a convexity in the Alpental Valley.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2

    While triggering a persistent slab avalanche is unlikely, the consequences are serious. There's still enough uncertainty that we can't rule out these avalanches. They can be dangerous and surprising and can catch even the most experienced backcountry travelers. Avoid hanging out, and grouping up in potentially consequential runout zones. This may include sparsely treed slopes or other terrain traps. Watch for obvious signs of instability like whumphing collapses, or cracks shooting through the snow.

    Persistent slab avalanches are still on our radar due to a weak layer of sugary snow that sits above and below a thin crust from early December. This structure continues to warrant respect, even though the chances of initiating a slide have decreased.  The layer of concern is a thin weak layer of small facets (and in places surface hoar) buried about 2-4 feet below the surface. Near the top of Washington Pass, this weak layer will be sitting on an icy crust. Further east in the zone, the crust has decomposed into a mix of melt forms and weak grains. At lower elevations, there's less concern for triggering this layer.

    (12/31/2020) Orange lines oultline crowns and debris from a very large (+D2.5) slab avalanche that occured during a widespread cycle on Dec 21st. The red line shows a small slab avalanche that occurred this weak, as loose snow pouring off the cliffs triggered recently drifted slabs about a foot below the surface. NE, 6500-6700ft, West Fork of the Methow River. Photo Josh Hirshberg.

Avalanche Discussion

About 8 inches of snow has accumulated since Christmas Day.  Observers noted loose dry avalanches running on steep southerly aspects Thursday in the Delancey Ridge area and as well as small and recent storm slabs that released below steep cliff bands earlier in the week. 

Many slopes ran during the widespread avalanche cycle of December 21st on the persistent weak layer that's now 2-4' below the surface. In some cases, this has allowed folks to cautiously step out and travel onto slopes safely if they know for certain the slope has already avalanched. New snow may obscure evidence of where these slides have run, creating continued uncertainty.   As we near the weekend storm cycle, we'll see if significant new loading awakens deeper instabilities in the snowpack. 

And Happy New Year from the Northwest Avalanche Center!  We hope you have a safe and healthy start to 2021. 

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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