Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You can trigger a fresh and sensitive slab on any slope steeper than 35 degrees as a significant storm takes aim on Mt. Hood.  Look for active wind-loading or recent wind lips to avoid large, sensitive slabs lurking at upper elevations. Use small slope tests to confirm a slab problem below treeline.

Problemi valanghivi

  • Storm Slabs

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

    Heavy snowfall Saturday night and Sunday will create storm slabs that you can trigger once 8" or more has fallen in your terrain. Use your pole to gauge the depth of the new snow above a refreezing crust layer from 12/18 as you travel below treeline. Multiple small, steep test slopes will help you confirm whether or not a storm slab has become reactive. If you find reactivity, avoid slopes steeper than 35 degrees, particularly those with convex rollovers.

    Example: Steep, convex rollovers such as this are where you are most likely to trigger a storm slab.

    Photo: Vetta Mountain Guides

  • Wind Slabs

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

    While the winds may be decreasing slightly at Mt. Hood, they remain plenty strong to transport the new snow and load lee slopes near and above the treeline. Cooling temperatures will make it easy for these winds to transport rapidly accumulating snowfall. Slabs may be large and sensitive. It may be difficult to distinguish between a storm slab and a wind slab in these conditions. As you move into terrain where you experience cracking snow surfaces, textured snow, or active wind transport, seek lower angle slopes (less than 35 degrees). Travel safely along ridgelines or windward (wind-stripped) slopes.

    (12/16/2021)

    Example: Blowing snow and fresh wind drifts in the East Central Zone. Expect wind slabs in the deposition zone.

    Photo: Kyle Hornor

Avalanche Discussion

Keep your attention on the recent storm snow and wind transport as a multi-day storm takes aim at Mt. Hood over the next 24 hours with anywhere from 6" to 2 ft of snow likely to fall on parts of the mountain. This is a good time to dial back your terrain selection and recognize that if the storm continues, avalanche conditions may deteriorate during the day.

Near treeline, forecasters found a generally right-side-up snowpack over 3+ (1m) deep on easterly aspects Friday.  There were not specific layers of concern heading into this weekend's storm cycle.  They noted ongoing wind transport higher on the mountain and a thin crust on the snow surface that capped 8-10" of snow from midweek.  While all elevations are looking much healthier snow depth-wise after a rough start to the winter season, creeks are definitely still open and present travel challenges. Recent lower-density snow likely settled somewhat on Saturday as ski areas reported a rain/snow mix at lower elevations. Winds ramping up with below-freezing temperatures likely continued to build wind slabs as several inches of new snow accumulated at upper elevations Friday night and Saturday.

Take some extra time to buffer for early season obstacles when planning your day out. 

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