Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

You’ll encounter dangerous avalanche conditions in areas where the wind has blown snow into stiff slabs. Winds have blown from multiple directions over the last few days, so don’t let your guard down as you change aspects. When in doubt, stick to more sheltered routes with lower slope angles to reduce your exposure. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    Strong winds and moderate amounts of new snow have created unstable, fresh slabs on wind-loaded features across the Mt Hood zone. Another modest system should deliver another 2-4 inches of snow (.25 SWE), which will start building a fresh batch of slabs. Winds will change more south and east, so you may notice wind slabs forming in unusual areas, like west aspects or across terrain features (cross loading). 

    Use visual clues such as blowing snow and textured surfaces to help you identify where the wind has been at work. Be suspect of terrain features that encourage drifting, such as the leeward sides of ridgelines, alpine couloirs, gully features, and cross-loaded depressions. Sheltered terrain with lower slope angles will offer safer riding opportunities.

    We have uncertainty regarding the sensitivity and distribution of weak snow above our early February crust. Any triggered wind slab could break wider and deeper than expected if it rests over weak snow 2-3 below the surface. 

    Storm Slabs:  Storm slab instabilities should settle out by Monday, but still consider it possible on unsupported, steep features that stayed dry. In any period with heavy snowfall, expect to find shallow reactive storm slabs. Look for hard-over-soft layering or cracking in the new snow to help you gauge the reactivity of the new snow. 

    (3/23/2023) 

    Dial it back if you notice shooting cracks or test slopes releasing easily. 

    Photo: Joe Dellaporta

Avalanche Discussion

The Cascade volcanoes have been in an active period. The most recent storm on Sunday delivered 6-8 inches of new snow on warming temperatures and clearing skies.

On Monday, look for a similar type of day with a couple of inches of new snow, strong alpine winds, and freezing levels hovering near 6000 ft. With these higher freezing levels and possible sun-breaks, look for wet snow to materialize at middle and lower elevations. The forecast team suspects a new crust below 6000 ft should limit wet loose avalanche types, but still keep an eye out for weakening surfaces if you notice the crust breaking down. 

Backcountry travelers reported numerous avalanches on Sunday. The warmer temperatures were a shock to the cold, dry snowpack. This warm-up led to multiple natural and human-triggered storm slabs (observation here) in more sheltered areas. Observers also reported sensitive wind slabs on Pea Gravel Ridge and unintentionally triggered a small slab (D 1.5) in wind-drifted snow.

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate avalanche forecast by submitting your observations here. 

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