Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

A storm will bring an uptick in avalanche danger on Saturday. Expect reactive slabs of wind-drifted snow, and use a cautious approach on steep, wind-sheltered slopes if you find over 6 inches of new snow. Avoid travel on steep slopes with fresh drifts  and don’t ignore obvious signs of instability like shooting cracks or whumphs.

Problemi valanghivi

  • Wind Slabs

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

    New snow will drift into reactive soft and hard slabs across exposed middle and upper elevation terrain. These slabs may not be that thick, but they could be easy to trigger and propagate wider than you may expect if they form over weak snow surfaces from the recent high pressure. 

    These wind slabs will be most prevalent on the downwind sides of ridges, below cornices, and beneath rock bands. Look for blowing snow, dune-like drifts, and sharp cornices to help you identify what slopes are loading up. Stiff snow surfaces and cracks shooting out from your feet or machine are obvious clues that you found a slab. You can reduce your exposure to this problem by sticking to ridges and slopes under 30 degrees. 

    If you find over 6 inches of new snow, it may be possible to trigger shallow storm slabs in more wind-sheltered terrain. Carefully assess the new/old snow interface before committing to steep slopes. 

    (3/14/2025)

    Blowing snow and drifted ridgelines are good indicators that reactive wind slabs may exist on the slopes below. 

    Photo: Joe Dellaporta

Avalanche Discussion

Snowfall totals Friday night into Saturday remain uncertain, and that uncertainty carries into this avalanche forecast. If we receive more than 6 inches of new snow, avalanche danger will likely rise toward Considerable in wind-loaded terrain above 6000 ft. Another uncertainty in this avalanche forecast is the presence of weak surfaces on many slopes, especially in more shaded mid-elevation terrain. Over the past days, avalanche professionals have reported a mix of surface hoar and near-surface facets above the February 7th crust.  Southerly aspects formed a thin, breakable sun crust that would at times have surface hoar capping it. If these weak grains get buried intact, we could see avalanches breaking wider and easier than usual. Will this happen though? We’re not sure - but it's good enough to step it back and dig around as you move through the new snow. Quick hand pits or shovel tilt tests can be effective tools for identifying shallowly buried weak layers as new snow piles up. 

Since February 7th, Mt. Hood picked up 8-10 inches of snow that fell over a crust. Strong winds accompanied this storm and produced thick, reactive wind slabs across exposed mid- to upper-elevation terrain. A couple of these avalanches broke 3-4 deep and propagated widely during avalanche mitigation work. One of these avalanches was suspected to fail on the 2/7 crust. As high pressure took grip, avalanche activity subsided, and east winds ramped up. These east winds raked through the Timberline areas and created variable surface conditions in the alpine. 

We could really use the observations as snow stacks up. Let us know what you see by submitting an observation here or on the AvyApp.

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