Bollettino valanghe

West Slopes South

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto last year. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Sunshine and warm temperatures on Wednesday will heat up the fresh snow, making wet avalanches likely. Watch for rollerballs, recent avalanches, or wet surface snow—if you see any of these, avoid steep terrain nearby. Above 5000 ft, human-triggered wind slabs will still be possible, especially in complex and confined terrain near ridgelines, cliffs, or gullies. With multiple hazards and limited observations, stay heads up, start small, and be prepared to make your own stability assessments if you venture into steeper terrain.

Problemi valanghivi

  • Loose Wet

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

    Wet loose avalanches in the new snow will likely be the most common problem on Wednesday. At upper elevations, these slides should remain confined to the recent snow and likely run on the 4/7 crust. However, we don’t know how strong or widespread that crust is. At mid-elevations, it’s possible a deep load of new snow is sitting on wet, unfrozen surfaces—here, wet avalanches could gouge deeper and grow large. While we’re not expecting consequential slides to start at lower elevations, slides from above could run far into those zones. These wet loose avalanches are relatively straightforward: look for the obvious signs noted in the bottom line, and change aspects or slopes if you spot red flags.

    Unfortunately, we also need to consider less likely but more dangerous wet instabilities. Wet and glide slab avalanches, cornice failures, and large chunks of snow falling off rocky faces (“blob-a-lanches”) are still possible. These are unlikely, and you probably won’t be the trigger—but if one goes, it could be large and destructive. Managing this kind of uncertainty is a personal decision, but it’s important to acknowledge the risk and plan your travel accordingly. If you’re traveling on or below avalanche paths, move quickly and avoid lingering to reduce the chances of being in the wrong place at the wrong time.

    (2/23/2025)

    Small roller balls and wet loose avalanches near Paradise. Once things warm, expect slopes to shed their new coat on Wednesday.

    Photo: NPS Rangers

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Moderate to strong winds have drifted the recent storm snow into slabs that may still react to your weight on Wednesday. In favored start zones, some of these slabs could be a few feet deep. Time and mild temperatures will help settle things out, but so soon after formation, steep and consequential slopes with wind-drifted snow should be treated as guilty until proven innocent. Look for textured surfaces and chalky or pillow-like drifts. Once you've identified possible wind slabs, either steer around them or be confident in your assessment before committing.

    Shooting cracks and recent avalanches are clear signs, but a day out from the storm, you may not get such obvious warnings. With a big new load and plenty of wind, expect steep slopes near ridgelines to be holding wind-drifted snow.

    (3/20/2025)

    A wind slab avalanche triggered by a snowboarder in the Crystal area. The crown was as thick as 2 feet deep and failed near the top of a confined chute/gully. 

    Photo: Reid Pitman

Avalanche Discussion

After barely a break in the action after the rain storm, 6–14" of new snow fell at middle and upper elevations Monday night through Tuesday afternoon, with a bit more still possible. Snow depths vary greatly with elevation. NWAC forecasters near White Pass observed blowing snow from every which direction and reactive but small wind slabs.  

If you’ve been following the forecast, you’ve heard us talk about uncertainty nearly every day—Wednesday is no exception. The snowpack has taken punch after punch: wind, rain, snow, sun—rinse and repeat. What it hasn’t had is consistently cold temperatures to lock things up, or enough warmth and water to complete a full spring transition to well-drained melt forms. Instead, it’s stuck somewhere in the middle: free water moving about, some wet layers and interfaces, and a significant portion of the snowpack that is still dry and wintry. In other words, it's not frozen, nor has it fully transformed. What it is, is uncertain. To top it off, we have very little recent information from the backcountry.

Here’s what we do know:We just got a load of new snow and wind, and now things are going to warm up. Dry and wet avalanche problems are overlapping across many slopes, and conditions are complex. You’ll need to make careful assessments, build a wide margin of safety into your plan, and approach each slope with an open mind. While most avalanches should be relatively small and limited to the recent snow, we can’t rule out a large and destructive slide.

Regioni coperte