Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Light Snowfall and increasing wind speeds will bring an uptick in avalanche danger across wind loaded terrain around Mt Hood. Some of these wind slabs could trigger easily if they form over weak surfaces. Look for signs of instability and consider steering around steep terrain that appears freshly drifted over. 

Problemi valanghivi

  • Wind Slabs

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

    The New Year will bring a fresh batch of shallow wind slabs that may be primed for human-triggering. In some areas, these wind slabs may form over a layer of surface hoar that resulted from our recent clear and calm nights. If this does happen, expect slabs to break easily and potentially propagate widely.

    On Wednesday, be suspicious of any terrain features that encourage drifting. You can typically find these slabs on the leeward sides of ridgelines and canyons, gully features, below cornices, or in cross-loaded depressions. Shooting cracks, hollow-sounding snow, and snowpack collapses are obvious signs of instability that you should not ignore. Sheltered terrain with lower slope angles will offer safer riding opportunities.

    Additional Discussion: New snow may also camouflage the older, larger wind slabs that formed during our loading event that wrapped up on 12/30. These hard slabs will likely be stubborn and may show minimal signs of reactivity - but if they do fail-  they may break several feet deep. Consider this low probability, high consequence situation before skiing or climbing in consequential alpine terrain above 6500ft. Check out the photos in the gallery for more information. 

    (12/30/2024)

    Use small test slopes or quick hand pits to help you identify how the new snow is bonding to the old surface. Cracking like this is a good reason to dial it back. 

    Photo: Joe Dellaporta

Avalanche Discussion

The short-lived high pressure offered an excellent opportunity for backcountry travelers to enjoy calm wind speeds and deep riding conditions thanks to our recent storms. This high pressure was also responsible for creating a fresh crop of surface hoar that backcountry travelers found in most open areas on Tuesday. The Mt Hood Meadows Pro Patrol found this surface hoar extending to 7000’ in their terrain. 

While this Tuesday night system won’t be a big snow producer (.4-.5 SWE), it could be enough to create problems in select areas where surface hoar gets buried in-tact, especially in areas that build a cohesive slab like wind loaded terrain. High winds are forecast to arrive as precipitation ramps up, which will hopefully destroy this weak surface grain. But unfortunately, we won't really know until the storm plays out. So, if you plan to head out on the New Year, ease into terrain slowly and investigate how the new snow is bonding to the pre-existing surface. Shooting cracks, snow sliding easily, or recent avalanches are all great reasons to dial it back. 

On Tuesday the Mt Hood Meadows Pro Patrol also reported triggering a couple of large avalanches in some of their heavily wind-loaded alpine terrain. One of the larger releases at 7200 ft on an E aspect featured surprisingly wide propagation and broke 1-3ft deep. Most of these older slabs are likely becoming more stubborn to trigger, but not necessarily impossible. These larger control results are a good reminder of the potential size that we're still dealing with in wind loaded, alpine terrain. 

Let us know what you see by submitting a public observation. 

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