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
2 · Moderato
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In sintesi

The damage from Wednesday's major wind event has been done, and thick hard slabs continue to lurk at upper elevations, potentially far down on the slope. Cornice fall may be most likely to trigger these. Rain will fall on previously dry snow at most elevations, create conditions wher you can initiate an wet avalanche on a steep, open slope.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    Although shallow amounts of recent snow will continue to transport at the highest NWAC forecast elevations to form shallow slabs you can trigger, the older, stubborn slabs remain the major story. These these were still reactive to hand charges on Friday as evidenced by the size 2.5 hard slab in the photo icon with a 2-6 ft crown. This would be difficult to survive. The failure occured at a subtle weakness above a crust. While we think you'd be quite unlucky to trigger one, cornice fall or snow falling off rocks or cliffs might increase the risk. You can further reduce your risk by putting some distance between yourself and steep, unsupported and heavily wind-loaded slopes. The largest and most reactive deposits may be well below ridgelines  on mid-slope features and rollovers in the terrain.  Unfortunately, you are unlikely to get feedback from these wind slabs until they break.

    (3/6/2026) An explosive tirggered hard slab avaanche in upper Heather Canyon.   HS-AE-R3-D2.5-U @ 7200', NE aspect   Photo: Joe Dellaporta

  • Loose Wet

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

    A warming trend will destabilize snow surfaces as previously dry snow becomes moist or wet. Although widespread wind affected snow may limit the potential for natural wet avalanches, this snow is still susceptible to human trigger. Look for sticky, wet snow that you sink into past your ankle to identify potential problem areas. Test this snow on a small test slope to see if it entrains as it moves down hill or just halts. If it wants to gather more snow, then steer clear of longer open slopes where a fan-shaped wet loose avalanche could push you into a terrain trap or become large enough to harm you.

    Example: A wet loose in lower White River Canyon entraining recent cold snow.

    Photo: Joe Dellaporta

Avalanche Discussion

Dry to wet transitions often add some uncertainty to the forecast. We have to ask ourselves questions about how old hard slabs will respond as they warm and become more flexible. There's some evidence to suggest that they could be slightly easier to trigger. And for how long will that slightly increased sensitivity exist? Don't get us wrong, the odds of triggering a large, old wind slab are very low, but these are the types of avalanches that would be difficult to survive, so they are very worth your attention. The best way to manage uncertainty is by reducing your terrain selection. Once temperatures cool back down by later in the weekend, the problem is kaput. This could occur sooner than we suspect if high winds firm up these upper elevations despite the warm temperatures on Saturday. We've seen this process play out many times on Mt Hood, but cloudy skies may limit the radiational cooling for this to occur.

As of Friday evening, the warming trend has started on Mt Hood. Clouds kept temperatures cooler around Timberline and the western half of the mountainon Thursday and Friday while most areas further east experienced partial sunshine. But Friday was warmer, with freezing levels climbing into upper elevations by late in the day. This sets up a crust by Saturday morning on sun-exposed slopes. Prior to the warmup, Mt Hood picked up 6-12" of fresh snow since Wednesday morning with strong to extreme winds that gradually eased by mid-day Thursday. Areas further west in the range picked up significantly more snow, while areas further east were "snow-shaddowed " during the storm.

NWAC forecasters and Mt Hood climbing rangers traveled to the NW side of Mt Hood, up to the top of the middle elevation band. They encountered stubborn, stiff slabs formed by the recent extreme W winds well bonded to an 8" thick layer of wet snow that had yet to refreeze. The recent snow was creamy on lee aspects and blasted along ridgelines. They did find a layer of buried surface hoar near the 2/13 interface, about 6" above the 2/7 crust. They did find some sudden planar results in compression tests, so it continues to be worth monitoring. The 2/7 crust has some weaker grains above it, but these are rounding and gaining strength quickly. Currently it is highly unlikely that you could trigger one of these layers, but it's not completely impossible. If you head to the north side of Mt Hood, it's worth digging around a bit and being aware of what may lurk in the middle of the snowpack. These weaknesses are limited to cold, shaded slopes and we generally believe they are on their last legs.

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