Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

It may be another moderate danger day with wind slab concerns, but that doesn't mean it's the same as the last few days. New overnight snow and wind will mean you'll find more wind slabs that could react to a human trigger, leading to a shift from the lower end of moderate on the danger scale to the upper end of the level. Search out newly drifted pockets of snow in near and above treeline elevations, and steer around them on steep slopes. 

Lawinenprobleme

  • Wind Slabs

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

    A storm is forecasted to bring 6-8" of snow and moderate to strong winds overnight. Instabilities will likely peak early morning before snowfall rates and wind decreases. You may find wind slabs a foot or deeper in the new snow, where it could be possible for you to trigger a small or mid-size avalanche. If more snow falls or wind redistribution occurs than expected, avalanche danger could be higher than forecasted. 

    Search for newly drifted snow in the usual suspect locations like on the leeward sides of ridgelines, in gullies and around rocky outcroppings. Drifts could appear as smooth pillows or textured surfaces, and feel slightly stiffer than nearby non wind-affected surfaces. If you experience long cracks shooting out from under you, that's an indicator of weakness in the new snow layer, and one of the best clues to avoid nearby steep slopes. Friday's an excellent day for checking how well the new and old snow layers are bonded by using hand shears. Small test slopes are also a good way to test for shallow wind slabs. In areas that you find wind slabs or see other indicators of weak snow, steer around slopes greater than 35 degrees. 

    An old photo of very small wind slabs breaking on the Shuksan Arm, which is similar to what you might encounter on Friday . Note the cracks shooting out from the skis, indicators of weak surface layers. 

    Photo: Adam Ü

Avalanche Discussion

The sun may come out in the afternoon, and there is a chance that small wet loose avalanches could occur on steep, south-facing slopes. If the sun doesn't come out, lower elevations may have moist snow and we could see rollerballs or small wet loose avalanches on steep slopes. Dry loose avalanches may occur in steep, non-wind affected terrain at upper elevations.

We received reports of rain falling up to 6000ft which started about 4pm Thursday. Cooling temperatures should transition the rain to snow soon, and we may find a moist layer or a crust beneath the new snow layer. A warmer start to this storm could also indicate better bonding with the old snow layer, but that waits to be seen. 

Avalanches that occur on Friday will probably fail within or just under the new snow, although at above treeline elevations there's a small chance that avalanches could fail deeper, on few-day-old slabs, like the one found in THIS observation on Wednesday. This was a very helpful observation for us, as it verified our forecast, showing that wind slab avalanches were still possible to trigger in isolated above treeline locations. Another factor to consider for Friday is that slabs could slide easier on south-facing surfaces where previous sun crusts formed. If you have any doubt about conditions or find more reactive slabs than you expect, you can always detour towards lower angle terrain. 

 

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