Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

If you choose to travel in the mountains on Sunday, do not get lulled into your standard method of approaching terrain after a storm. Dial back your terrain choices and realize that the snowpack is showing plenty of signs that it is unstable. Avalanches will occur on Sunday and have the potential to be large and deadly.

Avalanche problems

  • Persistent Slabs

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

    On Saturday, a large (D2.5) avalanche was human triggered in the Crystal Backcountry. Although this slope was wind-affected, it is believed that the slab broke on the Mid-January (1/13) crust/facet combo which has been the culprit of avalanches across the West South for the past week and a half. The fact that we continue to see avalanches on this layer should continue to remind you that it is not going away quickly and that these avalanches are unpredictable and dangerous. They can be remotely triggered from long distances away, break easily, propagate widely, and run quickly. The main weak layer is now 3 or more feet deep in most locations and this weak snowpack structure has been positively identified throughout the zone. In some areas, a second weak layer exists 2 feet or more down from the surface. Give all slopes 30 degrees or greater a wide berth as we navigate this tricky snowpack.

    (2/6/2021) This slab was intentionally triggered by a small cornice drop on Saturday (2/6) in the Crystal backcountry. It propagated widely and is believed to have run on the Mid-January crust/facet combo. [E aspect, 6300'. Photo: Jeremy Allyn]

  • Storm Slabs

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

    Continued precipitation focusing on the volcanoes and strong winds near the crest should continue to build slabs on top of those persistent weak layers throughout the zone. These slabs may have multiple density breaks within them due to fluctuation freezing levels, wind, and different periods of precipitation intensity. Take a look at these density breaks to see which ones could be a point of failure in your area. You can use test slopes, upslope tests, or hand-pits as you travel to give you quick information, but you will need to dig to get the full picture about how these slabs are interacting with the persistent weak layers. Triggering one of these slabs on Sunday could cause a ripple effect where the slab steps-down to trigger those persistent weak layers, creating larger and more destructive avalanches. If you find instabilities during your testing or notice fresh/recent avalanches, avoid terrain 30 degrees and steeper.

    (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

Observations have been limited due to the ferocity of the storm and the uneasiness we feel about the snowpack. However, we received a report of a large avalanche near Crystal, and a good public observation from Friday confirmed the weak snowpack structure at White Pass. NWAC forecasters were able to identify a similarly weak snowpack structure at Paradise on Thursday just as the storm was ramping up. We do not expect a widespread natural avalanche cycle on Sunday, which has allowed us to drop the hazard to Considerable. However, lots of recent avalanches, buried weak snow grains, heavy precipitation, strong winds, and continued precipitation in some areas is enough to keep us on edge going into Sunday. Do not be surprised if you come across some natural avalanches on Sunday, particularly during periods of intense precipitation. Human triggered avalanches are likely to occur. You should dial back your terrain choices from what you normally pursue at Considerable danger. If you do head out, use caution and let us know what you see by submitting a public observation.

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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