Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

With a return to wintery weather, be on the lookout for fresh pockets of wind-drifted snow as you crest into the wind zone. Steer around steep wind-loaded terrain if you notice active drifting or shooting cracks under your feet or machine. The likelihood of triggering large wet avalanches is decreasing, but the consequence remains concerning. 

Problemi valanghivi

  • Wind Slabs

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

    We’re getting just enough new snow and wind that small wind slabs may form in exposed terrain. Expect these slabs to grow in size and increase in sensitivity as you gain elevation. Start thinking about these slabs as you move into exposed terrain. They’ll often form on the downwind sides of ridges, beneath cornices, or aprons below chutes and gully features. Keep an eye out for obvious clues of instability, such as shooting cracks or stiffer over softer layering. 

    A cooling trend should help new snowfall on a favorable structure, but keep small storm slabs in mind if you find over 6-8 inches of new snow, particularly on steep or unsupported slopes.

    (3/22/2025)

    You can use small test slopes to gather valuable information about the reactivity. Cracking like this are good reasons to dial back your terrain selection. 

    Photo: Joe Dellaporta

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2

    The wet snow problem is trending downwards, but with just enough recent activity and another somewhat mild day, water will continue to percolate, maintaining the wet avalanche threat (loose and slab). Pay attention to surface penetration and the extent of the refreeze process. If you find yourself in unsupportable, wet snow, keep it dialed back and don’t linger under larger terrain. In areas where you find a more supportable crust, still, be cautious and consider digging down to see how thick the surface crust is before easing into bigger terrain. 

    Unfortunately, wet slabs are incredibly difficult to forecast and manage; therefore, the best approach is to keep your terrain selection simple until the snowpack has undergone a solid refreeze. 

    On Tuesday, an NWAC forecaster in the Icicle Creek area reported very large crowns from wet slab avalanches at upper elevations and widespread wet loose avalanches.

    (3/25/2025)

    A very large natural slab avalanche (at least D3) on Big Slide peak in Icicle Ck. This likely occurred March 23-24th. 7,500ft, SE.

    Photo: Josh Hirshberg

Avalanche Discussion

We’re finally making a return back to winter around the Cascades. Despite the cool-down, we’re still concerned about the lingering threat of wet slabs across the eastern zones. We’re coming out of a warm and active period that brought many large to very large natural wet avalanches. While temperatures are cooler, they're still mild enough (4-5000 ft freezing levels) for meltwater to percolate in the snowpack, especially at middle and lower elevations. It's a tricky problem to predict and manage, so the best strategy to deal with this uncertainty is to approach terrain with extra caution until we know the refreeze is significant enough to eliminate this concern.

NWAC Forecaster Katie Warren traveled around near Mission Ridge today.  She reported improving conditions with cooler temperatures but plenty of wet snow lingering under a thin crust and in more wind-sheltered terrain. Check out here full observation here if you venture into this part of the zone. 

If you get out into the mountains, let us know what you see by submitting a public observation here. 

 

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