Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Warm temperatures and rain are creating dangerous conditions. Wet loose slides may run naturally and could grow large on steep, large terrain features. Best to step back from steep slopes at mid and lower elevations while rain falls on a previously dry snowpack. 

Avalanche problems

  • Loose Wet

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

    Temperatures are on the rise, and rain is expected to fall up to at least 4,500ft on Tuesday. Dry snow is becoming damp, and wet loose slides are running. A number of slides were observed on Monday and ran up to D2 (Large) on the west side of the Pass . As warm temperatures bump over to the east side on Tuesday, we expect to see continued activity. These slides can entrain a significant amount of heavy snow and could pack a punch. Wet loose slides could also trigger larger wet slabs in some cases.

    Wet slides often start from trees or rocks shedding snow onto slopes below, but you can also trigger them with your skis or snowmobile. Look for signs of instability that include rollerballs, or fresh wet slides. It'll be a good day to limit your time spent underneath steep slopes where slides could run, especially if the snow is very wet and heavy.

    Example photo: If you see rollerballs, wet loose avalanches could be triggered or may occur naturally. 

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    At upper elevations where new snow has remained dry, check and see how it reacts on steep slopes. Slabs could be more reactive in areas of recent wind loading, but with warming temperatures we may see an 'upside down' storm layer. You can evaluate how well the new slabs are bonding with simple tests like slope cuts, skin track tests, and hand shears.

    There's a small chance that even if you trigger a small slab, it could step down to a deeper slab. If you find signs of instabilities like shooting cracks or easy failures with tests, than steer away from steep large or consequential slopes. 

     

    (12/1/2023)

    Shallow but fairly wide natural soft slab on a NE aspect at 6,300ft in Rock Mountain's East Bowl.

    Photo: Matt Primomo

Avalanche Discussion

Over the weekend we didn't see large weather inputs, with light to moderate wind (previously strong) and only a few inches of new snow.  On Sunday backcountry users on Lichtenburg reported very small avalanches on stiff wind board. You can read their observation HERE. On Saturday, observers on Lichtenberg Mtn reported areas with significant wind-affected snow (recent east winds) were mostly difficult to trigger or crack. They also reported a zipper crust was most pronounced above 5,000ft with soft snow and good skiing below. On Friday, observers in the Skyline Lake area reported cracking in fresh wind slabs at low and middle elevations and some light rain in the afternoon. 

Stevens Pass picked up over a foot of new snow on the 17th with intense snowfall rates and periods of strong west wind. Numerous triggered and natural avalanches in the new snow were reported. It's been 10 days since some very large avalanches ran on deeper weak layers within the Solstice Crust sandwich.  Heavy snow on the 17th could have been enough to re-activate these deeper weak layers, especially in the eastern end of the zone. If you see evidence of any recent avalanches, please submit an observation. The Solstice crust is now at least 5 feet below the surface in much of the zone. The weak layers consist of faceted melt forms, and some snowpack tests have given sudden and propagating results.

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