Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired last year. You’re viewing past conditions, not the current bulletin.

Highlights

Stick with simple, lower-angle terrain to reduce the risk of triggering an avalanche. It’s still possible to trigger a larger avalanche that releases in deeper layers in some parts of the forecast zone. Stay alert to warming affecting new snow, especially if the sun comes out. 

Avalanche problems

  • Storm Slabs

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

    By Sunday morning, many areas will have seen up to 2’ of new snow from the latest storm. This is on top of all the other snowfall from the past week. New snow instabilities tend to stabilize quickly. But the quantity of snow, a variety of weak interfaces, and the amount of avalanche activity in recent days point toward a more cautious approach.

    Start the day with a very conservative, assessment-oriented mindset. Gather information about the bond of new snow layers before considering anything bigger or steeper.  Slab avalanches are more likely in wind loaded terrain, but still look for instability in wind sheltered areas as well. You could find more dangerous conditions farther west in the forecast zone where there could be stronger winds and more wind transport.

     

     

    (3/14/2025)

    A human triggered D2 (large) soft slab avalanche in the Baker backcountry. 

    (SS-AR-D2-I

    Photo: Dallas Glass

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    There isn’t much difference between how you would reduce your exposure to the persistent problem versus the storm slab problem on Sunday. But some areas harbor persistent weak layering under the topmost layers of snow in addition to the typical new snow and wind slab instabilities. An avalanche that fails at a layer of buried surface hoar or facets can propagate widely, be larger or deeper than expected, and generally take you by surprise. One more reason to reduce exposure to steep slopes on Sunday.

    The type and distribution of weak layers varies between buried surface hoar in Canyon Creek, facets over crust in the Sisters Range, and anything else that could be out there, given variation in weather and snowpack across West North.  These layers are gaining strength and probably becoming harder to trigger, but it wouldn’t be far-fetched to see a bigger or deeper avalanche either. 

     

     

     

    (3/13/2025)

    An intentionally triggered avalanche in North Twin Basin. The avalanche propagated approximately 120 ft and ran 500 vertical ft.  The persistent weak layer in this area was a distinct faceted layer above the AR  crust, 25-50cm deep. North aspect at 4700'.

    (SS-ASc-D1.5-O)

    Photo: Zack McGill - Cascade Mtn Ascents

Avalanche Discussion

Temperatures aren’t that warm, and the sun should stay hidden, but if either of these comes to fruition, then be ready for some wet avalanche action. Slopes below cliffs and rocky terrain or treed areas are usually the first to produce wet avalanches. Dry loose should also be on your radar if you decide to get onto steeper slopes.

Observers in the Baker BC reported heavy snowfall and smaller slab avalanches to 12” deep and easy to trigger. Most looked to have only involved the most recent layer of new snow and were generally on wind loaded slopes. The most interesting was this human-triggered avalanche at lower elevations above Bagely Creek. Numerous natural avalanches to D2 were also reported. In general, the likelihood of triggering or seeing an avalanche steadily increased throughout the day as the new snow stacked up and was drifted by wind.  An NWAC Forecaster at Schriebers/Baker NRA reported even more new snow - about 18" - but no natural avalanches despite improving visibility toward the end of the day.

Avalanche danger ratings for Sunday look similar to Saturday, but with the end of heavy snowfall and stormy conditions, the likelihood of triggering or seeing a fresh slab avalanche will be somewhat lower. At the same time, the recent history of avalanche activity and additional snowfall overnight means you should consider instability in many areas, not just specific ones. Avalanche danger ratings cover a range of conditions, not a specific type or amount of avalanche activity. So even though both days are Considerable, they are not the same day.

 

 

 

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