Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Sat
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 6 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche concerns will vary with elevation. Wet snow avalanches may occur on steep slopes at low and mid elevations, especially below cliffs and other very steep terrain. Higher elevations could see small slabs forming in new snow layers, particularly where wind has drifted snow into thicker deposits.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    New snow amounts are not impressive, but the warming trend at higher elevations could create shallow new-snow instabilities. Look for strong-over-weak layering as you gain elevation, and use hand pits and test slopes to evaluate bonding between new snow layers.

    Winds are not forecast to be particularly strong, but you are still more likely to trigger an avalanche on wind-loaded slopes that hold slightly thicker and more sensitive slabs. Unstable slabs might also be found at and below 5000 feet in the morning if colder, drier snow falls overnight.

    (12/18/2020)

    Storm slab avalanches can fail at the old-new snow interface or within the layers of new snow.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    The number and size of wet-loose avalanches on Friday are up for debate, but it is a given the upper snowpack is currently moist or wet up to 5000-5500 feet. It should mostly stay that way with rising snow levels and light rainfall.

    Avoid travel on or directly below slopes showing signs of wet avalanche instability, such as rollerballs and very small wet slides, or where the snow is wet and sloppy. If rainfall is greater than expected, we could start to see wet slab avalanche activity as well.

    (3/5/2026)

    Recent wet avalanches in West North that initiated at 5000 feet. They likely released during rainfall a few days ago.

    Photo: Jan Osobov - Cascade Mountain Ascents

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–3

    Persistent slab avalanches can be large, break wide across terrain features, and be triggered from a distance. The likelihood of triggering one appears to be decreasing as continued loading from rain and wet snow has not produced new slab avalanches in areas that were active recently. Numerous wet-loose avalanches in the past few days have also failed to pull out deeper slabs.

    Even so, this remains a high-consequence problem. Avoid large, open, steep terrain—especially where the snowpack may be thinner or more variable. Whumphing or shooting cracks are red flags, but don't count on getting warned beforehand. It’s possible to dig down and look for layers of buried surface hoar or facets and evaluate stability, but the easiest solution may be to avoid steep, unsupported slopes where these avalanches were reported recently. These layers could also wake up with a bigger shot of rain this weekend.

    (3/1/2026)

    A snowmobile triggered a slab avalanche in West North. Suspected to have released a layer of mixed surface hoar and faceted snow above a thin crust. North aspect at 5600'.

    (HS-D2.5-AMu-O)

    Photo: Lee Lazzara

Avalanche Discussion

Recent observations from across the North and Central Cascades show a mix of wet and dry instability depending on elevation and timing. In some areas, the main avalanche problem shifted from shallow new snow slabs in the morning to wet avalanches by the afternoon as temperatures climbed higher than forecast and thin clouds produced greenhouse conditions. Small natural wet avalanches were observed later in the day, and it was reported to be quite easy to get wet snow moving on very steep slopes.

Storm totals across the region generally ranged from about 4 to 10 inches of new snow. Ridgeline winds were moderate to strong at times, but widespread wind slab formation has not been widely reported. The fresh snow should bond reasonably well to the old surface in many areas, though warming temperatures and rising snow levels could quickly tip conditions toward wet snow instability at low and mid elevations.

Persistent weak layers buried deeper in the snowpack remain a lingering concern. These layers have produced large avalanches in parts of the range in recent weeks, but the likelihood of triggering appears to be decreasing. No recent slab avalanches suspected of failing on these layers have been reported, though isolated signs of instability, including whumphing, have still been observed in some areas.

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