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

Very dangerous avalanche conditions will develop near and above treeline as heavy rain and snow combines with warming and strong to extreme winds. Avoid all avalanche terrain connected to near or above treeline start zones.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Strong to extreme winds have created potentially very large wind slabs that you can trigger at the highest elevations above the 7500-8000 ft rain/snow line. Sustained wind loading may also trigger these wind slabs naturally in isolated areas. While you may not encounter this avalanche problem directly, you may be exposed to these very large (D3) avalanches if you linger in valley bottoms. Stay off of, and out from underneath steep and potentially wind-loaded slopes at all elevations.

    (2/20/2022) Example photo of cracking within freshly wind-loaded snow. Photo: Paige Baugher

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–2.5

    Dry snow remained above 4500 ft on Sunday with less sun and wind affected snow near treeline. As rain and snow intensify and snow levels push up to 7500 to 8000 ft late Sunday night and early Monday, we expect widespread natural avalanches at all elevations. Wet avalanches will likely originate near treeline or as a wind slab that entrains wet snow as it descends. Avalanches could be very large (up to D2.5). More widespread small to large avalanches are very likely. Avoid all open slopes connected to near or above treeline terrain. Additionally, stay off slopes steeper than 35 degrees below treeline.

    Example: Very large debris from a wet avalanche.

    Photo: Matt Primomo

Avalanche Discussion

NWAC professionals observed light snow at Mt. Hood on Thursday with rollerballs forming below treeline as an indication that wet snow was destabilizing. Most terrain below 7000 ft should transition to rain by Monday morning. However, heavy rain and snow may not develop until the day on Monday. Expect rapidly deteriorating avalanche conditions as the 1.5-2" of water equivalent changes conditions very rapidly on Mt. Hood. The initial precipitation should add to 6-18" of snow above a strong crust. By the time the snow changes to rain, expect 1-2 ft of snow above the crust. Monday is a good day to make a travel plan that avoids all exposure to near and above treeline avalanche paths, which in some cases may descend to valley bottom. 

Expect wet snow conditions on Monday.  Snow surfaces prior to the storm been are a mixed bag of cold, settled powder, hard old wind slab, and sun-affected snow. Observers on the north, east, and south sides of Mt Hood found generally stable conditions Friday and Saturday. At lower elevations and on steep southerly aspects, many rocks, tree stumps, and other ground hazards are shallowly buried under the recent snow. 

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