Avalanche forecast

East Slopes North

Northwest Avalanche Center
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Avalanche danger

Tue
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Out of date — this forecast expired 6 years ago.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

Large persistent slab avalanches are becoming less likely, though the consequences of triggering one could be high. Continue to practice safe travel, being conservative with regrouping locations. Small windslabs are possible in the alpine. Be mindful of steep south facing slopes in the middle of the day because wet loose slides may run if the sun is out. 

Avalanche problems

  • Persistent Slabs

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

    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 back in early December. This structure continues to warrant respect, even though the chances of initiating a slide have significantly decreased. The consequences of triggering a slide on this layer are high, because it could easily be large enough to bury or kill you. These dangerous and surprising avalanches can catch even the most experienced backcountry travelers. The best way to stay safe is to avoid the type of terrain where you are most likely to trigger one. Keep your distance from large slopes that are steeper than 35 degrees, especially unsupported and convex slopes. 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.

    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. Last Wednesday, observers reported whumpfing collapses and tests that indicated the potential to trigger avalanches on this weak layer, especially above 5,600ft. At lower elevations, there's less concern for triggering this layer.

    (12/23/2020) Persistent slab that likely ran on the Early December Crust. West facing slope in the trees at 6,800ft near Silverstar Mountain.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Moderate winds with some 3-5" of new snow may have created windslabs in the upper elevation, wind exposed terrain. Look at snow surface texture and feel for stiff snow over weaker snow to identify wind slabs. Use test slopes to check how well these slabs are bonding. Avoid wind slabs that rest on slopes steeper than 35 degrees if you find signs of instability such as shooting cracks. Slabs will be most reactive on very steep and unsupported slopes. 

    If the sun comes out for more than a few hours we could see a round of wet loose slides on steep slopes that face the sun. Stay tuned in to signs such as moist snow surfaces and rollerballs as clues that these could begin happening during the middle of the day. Loose dry slides may occur in the shade on steep slopes as well.

    (1/10/2020) Example wind slab near Cutthroat Pass, photo from last season.

Avalanche Discussion

On Sunday an observer in Cutthroat drainage found sudden test results within recent storm layers down about 12" and 24" on a northeast aspect at 6,500ft. Storm totals since Christmas are around 3-5" of settled snow. Previous surfaces were a mix of decomposed grains and wind packed particles in some areas, and weak snow over slick bedsurfaces in others. Observers have noted that many slopes ran during the widespread avalanche cycle of December 21st. In some cases, this has allowed folks to cautiously step out and travel onto slopes safely, if they know for certain that it already slid. This new snow may obscure evidence of where these slides have run, creating continued uncertainty. 

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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