Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

More snow, strengthening winds, and warming temperatures will increase avalanche danger on Tuesday. Pay attention to changing conditions and shift to lower-angle, sheltered terrain as the storm moves in. High avalanche danger is anticipated overnight into Wednesday morning.

Two deep snow immersion near-misses were reported on Sunday. Stay alert to creek holes, tree wells, and other entrapment hazards below the 2-3’ of recent new snow. Keep your partners in sight at all times.

Avalanche problems

  • Storm Slabs

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

    Fresh slab avalanches in the uppermost layer of snow were very easy to trigger on Monday. These slabs should gain strength and become harder to trigger, but look for yet another round of slab formation later on Tuesday as the next storm winds up. 

    You are more likely to trigger an avalanche in terrain where the wind is building thicker slabs. Drifting snow will show you which slopes are loading up. You might also find denser snow over softer layers of snow on any aspect, not just wind-loaded slopes.

    Check the bond of new snow layers using hand shears, test slopes, and stomping on wind-drifted features. Stay alert to signs of instability like whumping, shooting cracks, and recent natural or human-triggered avalanches. These are signs it’s probably time to back off towards mellower terrain.

    (12/16/2024)

    A thin but widely propagating slab avalanche on Monday in the Baker BC. Reactive slabs were found on all aspects.

    Photo: Jere Burrell - Guided Exposure

Avalanche Discussion

Keep an eye on slopes picking up sun in the morning, or all steep slopes if you experience rain or a sharp temperature rise. Look for signs of instability like rollerballs and snow shedding from trees and cliffs. 

Observers in the Baker BC reported very reactive conditions on Monday with shallow but widely propagating and easy-to-trigger slabs on all aspects. Fresh snowfall (about 6” ) and moderate winds didn’t make for truly stormy conditions, but it was plenty enough to produce slabs that bonded poorly to the soft, weak snow below.

After stating in yesterday’s forecast that no human-triggered slab avalanches were reported, a slew of obs came in reporting human-triggered slab avalanches after our 6 pm publishing time. While some were small, shallow slabs in the topmost layer of new snow (obs, obs), others were a bit bigger and deeper (obs, obs). 

We don’t know for sure if the larger avalanches failed in a layer of softer snow under the stiffest wind slab or faceted snow a bit deeper in the upper snowpack. The few reports of whumphing on Sunday also add to these unertainties, It may end up being a moot point with 2.5- 3.5” of rain falling well up into upper elevations on Tuesday night. Heavy rain will probably wet out or overload any weak layering that has persisted for the last few days.

Regions covered