Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 6 years ago.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

Highlights

Wind Slab avalanches will continue to be a concern on Monday despite the nice weather. As you ascend in elevation, be aware of wind-drifted piles of snow where you could trigger an avalanche more easily. Keep your eyes open for new rollerballs or the snow surface becoming wet and sticky if you find yourself enjoying some sunshine.

Avalanche problems

  • Wind Slabs

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

    A strong wind event redistributed snow in some unusual patterns this past week in the West South. We continue to receive reports of human-triggered Wind Slabs in the zone and that pattern may continue on Monday. We believe the most sensitive slabs to be on NE-N-NW aspects, but since we experienced a variety of wind directions, you should look for pockets of wind affected snow on all aspects. You are more likely to find these slabs as you ascend in elevation, with the possibility of them being large at higher elevations. You can look for smooth pillow-like piles of snow or textured surfaces to help you clue into wind deposited areas.  If you encounter firm, hollow-sounding snow, you could be dealing with more stubborn hard slabs. Use small test slopes to test the bonding and reactivity of these slabs. Windblown snow often accumulates on the sides of gullies, the base of cliffs, or on convex rollovers. These features will be more likely to produce avalanches.

    (12/27/2020) This large avalanche in the Crystal Backcountry was 2-3 feet deep and 200+ feet wide. It ran across 3 cross-loaded gullies and had an unknown trigger. [NE side of Crown Point ~6460'. Photo: Joe Hoch]

Avalanche Discussion

The snowpack around the West South contains an average of 20-35cm of snow over a prominent crust (12/21). Some areas have been stripped down to the crust by the wind, while other areas have wind drifted pockets as deep as 60-70cm. Any avalanche activity on Monday should occur above the crust, with weak snow grains just above the crust possibly causing a point of failure for larger avalanches. Crystal Pro Patrol recently had slabs release on these weak grains, breaking 1.5-2.5 feet deep. On Sunday, a large avalanche was found in the Crystal backcountry to have a 2-3 foot crown and an unknown trigger. This slide also ran on the 12/21 crust. These slides have been breaking in some surprising ways and are generally found on NE-N-NW aspects which have been wind-loaded.

With sunny weather in the forecast for Monday, it's worth mentioning that if you find yourself in the sunshine, there’s a chance you could encounter some Wet Loose avalanches. Keep your eyes open for new rollerballs or the snow surface becoming wet and sticky to help clue you into this possibility. If you see fan-shaped avalanche debris, head for shadier slopes. 

The 12/21 crust is very firm and travel conditions can be difficult because of it. Allow yourself extra time and look out for open creeks and other early season conditions at lower elevations.

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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