Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

A recent windy storm has left reactive slabs of wind drifted snow in exposed terrain across the zone. These are most concerning in upper elevation terrain and around some wind exposed middle elevations. Wet snow instabilities may materialize on south facing slopes from during sunny periods.

Problemi valanghivi

  • Wind Slabs

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

    Several inches of new snow, paired with strong wind speeds, created reactive slabs on Sunday. With wind speeds staying strong enough to move snow through Sunday night, expect continued reactivity at upper and some middle-elevation terrain. 

    Look for these slabs to be larger and more widespread as you gain elevation into the wind zone. Blowing snow and fresh cornice formation often point toward areas with wind loading and elevated danger. Look for the tell-tale signs of a wind-affected surface, such as ripples or dunes. Cracking or collapsing indicates you have found an unstable slab, directing you to a lower-angle slope.

    Additional Discussion:

    Lingering storm slab instabilities may exist in steep or unsupported terrain closer to the cascade crest. If you plan on traveling in these western parts of the zone, approach steep, open terrain with some suspicion. You can use a small test slope or simple hand pits to help you gauge the reactivity of the recent storm snow. 

    (1/6/2025)

    Avoid steep, wind-loaded features if you notice cracking or fresh ripples at the snow surface. 

    Photo: Joe Dellaporta

  • Loose Wet

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

    Partly cloudy skies may supply just enough filtered sunshine to create wet snow instabilities on solar aspects. Anytime the sun pokes out after fresh snowfall (especially in March), expect some level of wet snow instabilities to form. Pay attention to your aspect, timing, and the snow surfaces around you. Consider moving to a shader aspect once you notice rollerballs shedding or sticky, gloppy surfaces under your feet or machine. 

    (2/26/2025)

    Rollerballs are a precursor to wet loose avalanches. 

    Photo: Dallas Glass

Avalanche Discussion

This has been a favorable storm cycle for the southern zones and volcanoes. Storm totals have ranged from 9-14 inches across weather stations, with the most reported around Bumping Lake, Chinook Pass, and the South Fork of the Tieiton. Unsurprisingly, backcountry travelers traveling in the nearby west south zone reported a round of reactive wind and storm slabs. You can check out their observations here (North Fork of the Tieiton/ Mt Adams/ Crystal Mountain).

While the weather on Sunday night and Monday should be favorable to help storm instabilities settle out, I would still approach any steep terrain with caution. We’re coming out of a stormy period that brought a good shot of snow and lots of wind, so expect more dynamic avalanche conditions as you gain elevation on Monday. 

You can help us gather more data by submitting an observation HERE or via the Avy App.

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