Bollettino valanghe

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Wallowa Avalanche Center
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Pericolo valanghe

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

In sintesi

The primary concern today is windslab formation at and near ridgelines on steep leeward facing terrain. New windslabs that formed during the snow and associated wind from yesterday could be very sensitive to the added weight and stress of a rider. It is likely that a rider could trigger an avalanche on steep leeward facing terrain at and near ridgelines today.

Problemi valanghivi

  • Wind Slabs

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

    The combination of new snow from yesterday (approximately 8" at 8200' in the Northern Wallowas) and moderate west southwest ridgeline winds has created windslabs on north, northeast, and east facing terrain at and near ridge tops. Windy conditions and intense precipitation were also observed in the Southern Wallowas yesterday. If you choose to travel at and near ridgelines today know that human triggered avalanches are likely on leeward facing, wind loaded terrain steeper than 35 degrees. Signs of wind loading and windslab formation include the presence of cornices and large pillow like formations on the affected slopes. Venturing out onto snow that seems hollow or drum like is another sign you might be traveling on a windslab. Recent new snow, the presence of wind transported snow, and hollow drum like sounds at the snow surface are red flags that cannot be ignored when considering recreating on steep terrain near ridge tops today. Cautious route finding and conservative decision making will be essential while recreating in high alpine terrain today.

  • Loose Wet

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

    Sunshine is in the forecast today for some locations and that means warming at the snow surface on south facing aspects. Sunshine and associated solar radiation has a dramatic weakening affect on newly fallen snow. When traveling in the mountains today keep an out for roller balls and small wet loose avalanches on sunny southeast,south, and southwest facing terrain. If you observe these red flag signs of instability it is time to avoid, get off of, or out from under steep solar affected terrain.

Avalanche Discussion

Yesterday I was ski touring in the Northern Wallowas. It started snowing by mid morning and was snowing above 5000' . It snowed off and on until about 3:15 PM. The snow was pretty heavy at times. I was traveling on an east facing ridge that picked up 3"-4" of snow throughout the day. Winds were light below treeline but picked up above 8000' . I detected rain affected snow 4"-6" under new snow all the up to about 7200' from Thursday's warm up. The soggy rain wetted snow may have formed into a pesky crust by this morning. As of yesterday the new snow had bonded well to the rain wetted layer. Otherwise good stability was observed. Snow pit stability tests showed continued right side up snowpack and moderate test results in the upper 12" . No propagation was observed and column sheers were resistant and planar. The snow depth at 8200' was about 8' (240 centimeters).

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