Avalanche forecast

West Slopes North

Northwest Avalanche Center
View on map

Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map
Out of date — this forecast expired 8 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Rain will transition to snow, and wet snow avalanche problems will transition to dry ones as the day progresses and you gain elevation. If you find drifts of snow 6 inches or deeper, steer around steep slopes, as it's likely these could avalanche with a human trigger- especially as they grow while snowfall amounts and winds increase in the afternoon. Sticky snow and rollerballs are indicators that wet avalanches could happen. 

Avalanche problems

  • Wind Slabs

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

    At upper elevations early in the day, expect a few inches of new snow being blown around—enough to trigger small avalanches. As the day progresses, increasing winds and continued snowfall will build larger, more reactive wind slabs. These avalanches could become large enough to bury and kill a person. At mid elevations, falling snowlines mean there may be little new snow and minimal wind slab development until later in the day.

    Carefully evaluate conditions as you travel. Look for signs of recent drifting, as wind slabs often form near rocky outcroppings, along ridgelines, and on the sides of gullies and rollovers. Pay attention to areas of thicker, denser snow, and watch for red flags like shooting cracks. Simple hand pits can help assess how well wind slabs or new snow are bonding to the underlying snowpack. Avoid steep slopes where you observe any of these warning signs.

    Example photo: Wind drifted snow around features like rock outcroppings, where it's more likely you can trigger an avalanche. Note the wind transported snow visible in this photo. 

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Fresh new snow that's still damp is where  you might see wet avalanche activity. Alternatively, an underlying moist layer could initiate combo wet/dry slide, which you'd probably find in the mid elevation band. There may not be much for natural activity, but if you venture out onto steep slopes, you might be able to trigger a slide. In this situation, keep peeking behind you, and if you trigger a slide, move off to the side of the slope before it catches you. If you see any rollerballs or wet slides coming down, steer around areas where this activity is happening or similar slopes.

    There's a small chance that glide cracks or avalanches could happen with this wet weather. If you see large, full-depth cracks in the snow, steer clear of areas beneath those cracks. 

    Example photo: Rollerballs initiating from trees and other steep, rocky areas. These are indicators that more wet avalanche activity could follow. 

Avalanche Discussion

There's a lot of uncertainty in the weather forecast, never mind large variations with this incoming weather throughout the zone. Slight shifts in both precipitation numbers and freezing lines could make for different avalanche problems and danger levels. Because of this, be sure to evaluate conditions during your outing. In the Heather Meadows area, we expect upper elevations could get a foot of snow Friday night through Saturday, but high snowlines mean that mid elevations might receive half that amount.  Snowfall amounts may be lower in other locations of the West North zone. 

Wet avalanche activity has been on the radar for days now.  Most old snow has already gotten wet and is probably less likely to slide. On Friday, a forecaster at Heather Meadows reported "greenhousing" with high humidity and warm temperatures, causing previously dry snow on north-facing aspects to rollerball, up through mid elevations. They also found that where melt freeze crusts had formed, on southerly aspects, the warmer, wetter conditions were keeping these crusts soft. We hope that given the warm start to the storm that we thought was going to initiate Thursday night but is starting Friday night instead, will result in snow bonding well to the underlying layers. 

Regions covered