Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

As the beautiful sunny weather beckons you to come to the mountains Tuesday, remember you can still trigger newly formed wind slabs. When you see smooth pillow-like features, experience firm hollow snow, or see sharp cornices, steer around nearby slopes greater than 35 degrees. As you ascend to higher elevations these potential avalanches may become larger and more prevalent.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Extremely strong winds pummelled the West-South during Monday’s storm and likely drove the snow into chaotic loading patterns in a variety of areas. You may find wind slabs well below ridgeline, along the sides of mid-slope features, and on exposed slopes at any elevation. As a result, you’ll need to keep a keen eye for signs of wind deposited snow. When you see fresh cornices, find smooth pillow-like deposits, or feel frim hollow snow, give nearby slopes greater than 35 degrees a wide berth. If you use the nice weather to travel to higher elections, expect wind slabs to be larger and easier to find.

    (11/28/2020) Textured surfaces like this indicate wind loading on nearby slopes.

Avalanche Discussion

Snow totals around the West-South vary a bit by location and windy conditions made measuring accumulations exceedingly difficult. In general, Paradise received 8-10” of snow, with Cyrstal, White Pass, and Mt St Helens adding 5-8” to their respective snowpacks. This snow accumulated on a new interface (11/30) that, in some locations, may make triggering avalanches easier. On slopes that receive direct sun, a firm crust formed last week. Reports from other zones showed the new snow did not bond well to this crust. At Crystal, White Pass,  the Tattosh Range, Snoqualmie Pass, and in the Teanaway River (East-Central) surface hoar was reported on shaded sheltered slopes prior to the storm. If you encounter buried surface hoar, avalanches could fail on lower angled slopes or trigger remotely. You’re most likely to find buried surface hoar at mid and lower elevations and in areas further east. 

Tuesday marks a transition day in the mountains from stormy and cold to warm and sunny. These days are often tricky to forecast. If the warmth and sunshine win out, you could see a few rollerballs and small loose wet avalanches from steep sunny slopes. Firm wind affected snow surfaces will take the sun longer to melt than areas of soft powder. 

The snowpack around the West-South is impressive for the first day of December. Most areas currently hold 3-6’ (90-180cm) of settled snow. Even though snow covers most objects many creeks remain open and require additional navigation. 

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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