Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Be aware of what's above you; very large and destructive avalanches may release from the upper mountain and run long distances as extreme winds, rain and high elevation snow pick-up again on Monday.  Smaller wet snow avalanches at lower elevations can be dangerous in extreme terrain or near terrain traps. 

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2.5–3.5

    Until the storm pattern relents, choose simple terrain and limit your exposure to areas where very large avalanches can start, stop and run.  

    Snow levels will oscillate between 6500-7000' Sunday night/Monday with another 1-1.5" of snow water equivalent forecast for Mt Hood.  This will follow the 4" of liquid water that has entered the snowpack between 7000-8000' since Saturday. 

    Wet slabs are highly unpredictable, failing as water runs through the snowpack and pools on crusts or weak layers in the snowpack. A very large wet slab avalanche would be unsurvivable. These may initiate in middle or upper elevation start zones and could run to valley flats and down canyon drainages.  While the likelihood of natural avalanches should tick down a notch Monday,  your best bet is to avoid all terrain connected to upper elevation start zones.

    Natural wet loose avalanche activity may have peaked already at lower elevations, however, a soggy, wet snowpack still requires your respect.  Steer around very steep slopes with deep wet snow, and use extra care around terrain traps.  Around the rain/snow line, you may see a higher likelihood of wet loose avalanches as the snow level bumps around. Cornices are likely to be weakened and may fail naturally.  Don't travel on or below slopes with large overhanging cornices. 

    Example: A very large D3 avalanche in Heather Canyon. running down to and along the canyon bottom.

    Photo: Joe Dellaporta

  • Wind Slabs

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

    Bouts of extreme W-SW winds will load lee slopes at upper elevations as the snow level dips slightly.  Dry snow avalanches that release at upper elevations may become very large and unsurvivable wet snow avalanches as they descend to lower elevations.  We are listing a different avalanche problem that results in the same travel advice - don't travel on or below large open slopes capable of producing large avalanches. 

    (2/12/2024)

    Natural slab avalanche entraining moist snow.

    Photo: Robert Hahn

Avalanche Discussion

It's wet and windy!  Over 4" of mostly liquid water has entered the snowpack below 7000-8000' since Saturday afternoon.  Due to the storm, observations outside of weather stations are extremely limited.  At mid-elevations,  Mt Hood pro-patrol reported wet, saturated snow extended down at least 2' from the surface Sunday morning.  

The last significant snow event brought 6-10" of snow accompanied by strong W-NW winds, producing some impressive wind slab activity. A very large natural avalanche failed on an E aspect in White River Drainage. Multiple size 2-2.5 (large) avalanches were triggered by MHM patrol on E and SE aspects, including this one. This activity likely involved the 2/13 interface, which may wake back up over this storm cycle.

In the gallery, we're including a variety of the types of wet avalanche activity we're expecting to see over the next few days. A crown profile from a recent large wind slab also shows the potential for structural weaknesses in the snowpack that can be exploited by rainwater moving through the snowpack and triggering wet slabs.

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

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