Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Avoid terrain that has evidence of being influenced by the wind. The snowpack needs time to heal and may not heal as quickly as you are used to. Buried weak layers are not going away anytime soon and should drive you toward conservative terrain. 

Avalanche problems

  • Persistent Slabs

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

    Continue to approach terrain over 30 degrees with caution in the West South as we navigate uncertainty around buried weak layers. You can dig down to determine the existence of these weak layers, but a single hole in the ground shouldn’t be a tool for ruling them out in your area. In some areas of the zone, these layers may be close to a meter deep and you may not experience signs of instability as you travel. Just because you are not seeing obvious signs of instability does not mean that you have chosen the appropriate terrain. We have some uncertainty about what it would take to trigger one of these slides at this point, but it could be a step down from a smaller avalanche, a snowmobile, cornice, or even just a shallower spot in the snowpack. What we do know is that if you trigger one of these avalanches and are caught, it would most likely be unsurvivable.

    (2/8/2021) This very large avalanche on Mt. Rainier was one of many avalanches viewable from Crystal Mountain on Monday (2/8). This avalanche likely occurred during the storm over the weekend. [Photo: Robin Pendry]

  • Wind Slabs

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

    Look for Wind Slabs to have developed on leeward slopes near ridgelines, or near rocky terrain such as cliffs and gullies. Convex rollovers or slopes over 35 degrees should be more prone to triggering avalanches, whether they are wind-loaded or not. There should be plenty of density changes and interstorm layers in the upper snowpack for you to investigate as potential failure points. As you travel, you can use uptrack tests or test slopes to see how the recent snow is reacting to your weight. Look for visual clues such as textured snow surfaces, freshly built cornices, or smooth pillow-like piles of snow to help you identify where the wind has affected the snow. In some areas, these visual clues may be hidden by low-density snow that fell on Sunday night. If so, try to feel for subtle differences in the snow as you travel. You could find that the snow feels firm and hollow, indicating a harder Wind Slab. You should avoid any slope greater than 35 degrees that you suspect is wind-loaded.

    (2/6/2021) Multiple slabs were observed on an E aspect at 6300' in the Crystal backcountry on Saturday (2/6). Deeper slides are suspected to have run on the Mid-January crust/facet combo while shallower Wind Slabs were also observed. [Photo: Jeremy Allyn]

Avalanche Discussion

Preliminary avalanche incident information Monday February 8th, 2021: Two snow bike riders were caught and buried by a very large avalanche in the mountains west of Salmon la Sac Sno-Park along Cle Elum Lake. One snow biker was partially buried and was able to dig himself out. The other rider was fully buried and killed by the avalanche. The avalanche occurred on a north aspect at 4400 ft in the Knox Creek drainage. This terrain lies in NWAC’s East Central forecast zone. Avalanche classification: HS-AV-R3-D3-O. 

All of us at NWAC want to extend our condolences to family, friends and the local community following this tragic event.  

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Crystal Mountain patrollers were able to get some visibility over toward Mt. Rainier today and confirmed a very large avalanche occurred. Several other widely propagating avalanches were spotted in the surrounding terrain. These all are suspected to have run between Thursday and Sunday and many of them look to have broken similarly to the persistent slabs we have identified elsewhere in the zone. Until now, we hadn’t seen any avalanches on these weak layers at Mount Rainier National Park, and although unconfirmed, we’ll take a leap of faith that these slides failed on one of our two layers of concern. We had positively identified these layers of concern near Paradise on Thursday just as the storm cycle was getting started.

We have had a lot of large and dangerous avalanches in the West South this past week and unfortunately, the setup remains for these slides to continue. You need to keep approaching terrain with caution and being suspicious of open terrain features greater than 30 degrees. There were multiple avalanche involvements and close calls this past weekend, including a good free lesson from Stevens Pass. Please be safe out there.

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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