Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You can trigger avalanches on steep slopes with wind deposited snow. Stay alert as you climb in elevation and look for signs of instability like cracking, collapsing, or stiffer over softer layering. Wet snow instabilities may develop on south and west-facing slopes during sunny periods. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    The recent new snow was accompanied by strong WSW winds, which built slabs ranging in size and sensitivity across the zone. These were reactive on Wednesday and with continued overnight loading, slabs may stay primed for a human-trigger on Thursday morning. You’ll likely find softer, more reactive slabs closer to treeline and thicker, hard slabs that may feel more stubborn in alpine areas. While these hard slabs may show less signs of reactivity initially, they could break in surprising ways and be far more consequential if triggered. 

    Wind slabs typically take a few days to heal up. Until they do, use visual and surface clues to help you identify where the problem lurks. Ripples, dunes, and fresh cornices are all signs of recent loading. You’ll typically find these slabs below exposed ridgelines, on the breakover of mid-slope features, or tucked in gullies and chutes on the upper mountain. Probe around feeling for stiffer snow and use small test slopes to help you gauge the sensitivity of the drifted snow. Shooting cracks, whumphing collapses, and recent avalanches are great reasons to dial it back. 

    Additional Discussion: 

    While the storm has tapered, storm slab instabilities may linger on certain terrain features in more wind-protected terrain. Evaluate for instability in the new snow and use caution on steep, unsupported terrain.

    (2/19/2025)

    It was easy to trigger cracks in wind loaded, unsupported terrain features throughout the day across the region. 

    Photo: Payton Schiff

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    The new snow will start peeling off solar slopes as skies clear. It may not take much time for the surface snow to react to clearing on south and west aspects. Rollerballs, pinwheels, are sticky-wet surfaces that are precursors of wet loose avalanches. These likely won’t be big, but it's best to not underestimate wet snow, especially in more radical terrain. Shift your aspect once you notice obvious signs of warming.

    (2/17/2025)

    Look for signs of unstable wet snow like this as the sun pokes out. 

    Photo: Joe Dellaporta

Avalanche Discussion

While the storm underproduced, weather stations still managed to pick up 7-9 inches by Wednesday evening. On Wednesday avalanche professionals at Mt Hood Meadows reported one natural, cornice triggered avalanche and reactive wind drifted snow that released easily with ski cuts. 

 The new snow rests over a crusts on most aspects. The big question for Thursday will be how the new snow bonds to this old snow surface. In some spots it may bond well and in others it could be a great bed surface for avalanches to run on. This will be a good day to use quick hand pits or simple uptrack tests to help you understand how the new load is bonding. 

 Observations have been limited on deeper weak layers around Mt Hood. However, further north observers are finding a new weak layer that was buried around February 13th. There have already been several avalanches reported on this weaker snow around Crystal Mountain, Snoqualmie Pass, and the Eastern Cascades. We have limited information regarding avalanches on this layer around Hood, but we have seen a few snowpack tests fail at similar depths (1-2 ft). 

 Will it be a problem around Mt Hood? Maybe, maybe not. The best strategy will be to pull out your shovel and complete a snowpack test before riding or climbing in steep terrain.

And lastly, the snow is deep. Deep snow immersion will be a real hazard for the next days at lower and middle elevations. Give treewells and creeks a wide buffer while keeping your partners in close sight. 

You can contribute to the avalanche forecast! Let us know what you see by submitting a public observation here. 

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