Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Heavy snowfall at upper elevations will likely result in a natural avalanche cycle in the night. Stability will improve throughout the day, but with the newly added load, stay off steep slopes, especially if there are obvious signs of instability like recent avalanches, cracking, or whumphing. Rain at lower elevations will leave the snowpack punchy and unsupportable, and wet snow avalanches could occur. 

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    An overnight natural avalanche cycle will probably occur Monday night during peak instability. Around 2 feet of snow is forecasted to fall overnight. Snowfall should taper off by 10am. It's likely that you can trigger a large, natural avalanche in the new snow, especially earlier in the day. Danger may be higher at the very start of the day, but stability is expected to improve as the snow settles.

    Snowlines wavered in the mid-elevation band for much of the storm. There probably won't be much snow at your starting elevation, but expect amounts to increase quickly as you make your way to upper elevations. Danger will increase as new snow depths increase. There is uncertainty regarding new snow amounts and how it will react at upper elevations. If you make it up there, be prepared to evaluate conditions for yourself. 

    The storm occurred with moderate to strong wind, so this new snow avalanche problem will probably be more reactive in thicker and heavier wind-loaded areas. During your outing, stay on small terrain before you head to any larger slopes. Evaluate the bond between the new snow layer and the surface beneath. Determine whether there are any weaknesses within the new snow layer, especially if it is wind-affected. Steer around slopes steeper than 30° where there is more than about 6" of snow present on the surfaces. 

    Example photo: A large storm slab avalanche which is similar to one that might occur Tuesday.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Rain at lower elevations isn't unusual this season. Ths snowpack is already moist and mainly transitioned into melt forms. The 2" of rain that falls at lower elevations overnight will maintain a soft, punchy snowpack. Wet loose avalanches may occur if you venture out on steep slopes. The snowpack is so shallow that they could run all the way to the ground. Wet snow may also continue shedding off steep, unsupported slopes naturally.

    Temperatures will slowly drop towards the end of the storm and snowlines will lower.  There might be small amounts of rollerballing in the new, moist snow in the rain/snow line vicinity. If you notice rollerballing or small wet slides, avoid steep slopes. If you're sinking into wet snow past your ankles, keep off terrain greater than 30°.

    (12/21/2023)

    A thin wet snowpack is breaking and gliding on this steep, vegetated surface. This could continue on Tuesday.

    Photo: Andy Harrington

Avalanche Discussion

Snow that fell Friday was redistributed in strong winds over the weekend. Slabs around 6"-12" deep were found, and cracking was observed but only one avalanche was reported. Beneath this redistributed snow layer at mid and upper elevations, a crust exists. From there to the ground, snow layers are moist with varying crusts. This is from about 5000ft and lower. We don't expect avalanche activity to occur beneath the crust in areas where the crust hasn't been completely softened by the warm temperatures and rain. 

As is the trend for this year, beware of early-season hazards like shallowly buried rocks and roots, and open creeks. Don't forget there's a solid crust beneath new snow layers in most areas, which may be slick in places. We hope you enjoy the snow that does exist, and happy holidays from the NWAC team!

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