Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Multiple parties were caught, carried, and partially buried on Saturday. Continued snow and strong winds will maintain dangerous avalanche conditions on Sunday. So dial back your terrain choices by avoiding all slopes over 35 degrees where triggering an avalanche is more likely.

If you are considering going to Mount St. Helens or Mount Adams, HIGH avalanche danger is expected and traveling in avalanche terrain is not recommended. Read the Mt. Hood forecast for additional information.

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    New snow is stacking up this week, creating numerous new snow problems for you to manage on Sunday. Slabs will be easier to trigger on slopes over 35 degrees, particularly if they're wind-loaded, convex, or unsupported. In some locations, you may remotely trigger slabs from nearby terrain. Any steep slope is capable of avalanching with this much snow, and if it's not a slab, it could be a loose. As you ascend in elevation, storm totals increase significantly, especially where the wind has created deeper drifts. Using uptrack tests, hand pits, or small test slopes can indicate how the new snow is setting up. But to assess the actual hazard, you'll likely need to dig down to the AR crust to get a feel for potential failure points. Depending on your elevation or location, this could be multiple feet below the surface. Keep it simple - avoid slopes over 35 degrees where avalanches are more likely until this storm has passed.

    (3/15/2025)

    A slab avalanche in Cement Basin that caught, carried, and partially buried a skier. They had skied several other runs without issue before triggering this slide.

Avalanche Discussion

The storm will rage on for the West South zone, particularly further south. If you hope to travel anywhere south of White Pass, you should digest everything you read here, and then read the Mount Hood forecast to clarify how potentially dangerous it will be. Rising freezing levels, strong to extreme winds, and heavy precipitation Saturday night into Sunday morning will create HIGH hazard in our zone's southern portion. Natural avalanches are expected, both dry and wet, loose and slab. Keep an eye on how the weather plays out wherever you are recreating. If the storm tracks further north than expected, large natural avalanches could follow and you should avoid all avalanche terrain.

Even if you're in the northern half of the zone, it will continue to be dangerous in the mountains. The snow has been piling up this week and we're measuring storm totals in feet throughout the region. A constant stream of avalanches has occurred as storms rolled through, increasing snow depth over the AR crust and creating numerous interfaces. The wind has also been a major player. On Saturday morning, the White Pass station recorded a gust as high as 91 mph. Backcountry travelers near Mount St. Helens, Crystal, and White Pass all reported being surprised by avalanches. In Cement Basin, a skier was caught, carried, and buried up to their waist. Near White Pass, skiers reported hearing whumpfing, long shooting cracks, and triggering a slab in treed terrain. On Mount St. Helens, a combination occurred when travelers heard audible whumpfing, then got caught, carried, and partially buried. 

Don't expect much to change on Sunday. More snow will only increase the depth of avalanches and create a new interface to manage. We're dodging bullets here with multiple caught and carried scenarios and avalanches breaking in surprising ways. Slopes are still primed for avalanche activity and reports of whumpfs and being surprised should have you dialing your terrain selection way back.

As the storm starts to fizzle, snow and wind could be replaced by rebounding temperatures or periods of sunshine. Any time the sun came out this week after receiving fresh snowfall, wet avalanche activity followed. It's not a slam dunk for Sunday so we're not listing it as an official problem, but you should have it on your mind for the rest of the season now that it's mid-March.

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