Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

The combination of several days of above-freezing temperatures, a cold winter-like snowpack, and known deeper weak layers make for particularly dangerous conditions. Avalanches may start to involve lots of snow and grow much larger. Limit any time you spend on or under steep slopes.

Avalanche problems

  • Loose Wet

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

    All sorts of shallow wet avalanches could occur on Saturday. Wet loose slides, cornices, snow shedding from rocks, and even shallow slabs. A poor overnight freeze could help keep this issue in check, but it won’t last long. Sunshine and rapidly rising temperatures will reinvigorate this issue. You may trigger slides on any steep slopes with wet manky snow, but they could also release naturally from terrain above you. 

    While these avalanches are a hazard unto themselves, they could trigger a more unpredictable wet slab or gouge into deeper snow layers and grow much larger. If either occurs, the scales are tipping and the mountains are shedding their winter coat. Figuring out exactly when this occurs is very tricky. Limit any time you spend underneath steep snowy slopes.

    (3/15/2024)

    Rollerballs and small wet loose slides from steep rocky terrain.

     

    Photo: Andy Harrington

  • Deep Persistent Slabs

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

    Weak layers from early February continue to linger in the snowpack. It’s hard to say what could wake them up, but this warmup adds a considerable level of uncertainty to the situation. In some sense, all bets are off. You likely won’t see any signs of deeper instabilities until the entire slope comes unglued. 

    There’s no magic bullet, no trick, no perfect observation. The only tool we have is avoidance. Any time spent in large avalanche terrain is simply a gamble, and the consequences are quite high. Choose routes that help you minimize or even eliminate the need to travel in places where larger avalanches may run or stop. 

    (3/7/2024)

    A widely breaking crown on the Conrad Glacier below Gilbert Peak. [N 7500']

    Photo: Andy Harrington

Avalanche Discussion

We’re on the front end of a prolonged significant warmup. Some sites have been above freezing since Thursday, others Friday. Different parts of the zone could reach their tipping points at separate times. Specifically, when and where is anyone's guess, but the setup is clearly there. Often we look to the three nights above freezing as a common rule of thumb, but that may or may not hold true. 

On Friday, a cool easterly breeze helped keep most of the wet avalanche issues in check a few small wet loose slides occurred, but in general, there wasn’t a significant amount of avalanche activity reported. As the winds decrease on Saturday, the full brunt of the warmup should be on display. 

Despite the winds, warm temperatures impacted the snow surface around the compass dial, reaching into all but potentially the higher-shaded aspects. Underneath the surface, the snowpack remains cold, dry, and wintery. That’s part of what makes this warmup so impactful. Several storm interfaces and persistent weak layers can still be seen all the way down to the Early February Crust and facets 3-6ft below the surface. We don’t have any recent direct observations of these older weak layers, but they produced a number of avalanches all across the zone over the last several weeks.

Regions covered