Bollettino valanghe

Central Cascades

Central Oregon Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Triggering a wind slab will be the primary concern for Saturday. The wind is actively moving snow to lee sides of ridges and other terrain features. This is contributing to building small cornices and loading slopes. Before committing to lee east and north facing terrain evaluate where the wind is causing snow to drift and accumulate . 

Problemi valanghivi

  • Wind Slabs

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

    Although I expect most human triggered wind slabs to be closer to the small side (D1), watch for those areas that act like a catcher's mit and collect blowing snow. The potential for triggering larger wind slabs exists in isolated pockets of terrain. 

    Blowing snow was observed near treeline on Friday. This will conitnue as long as there is soft snow on the ground avialable for the wind to move.

    Look for visual signs such as pillows of wind difted snow, and a wavy or uneven surface texture to indicate a surface may be wind loaded. Recently formed cornices can also be clues that wind slabs are present. If you see cracking in the surface snow or experience hollow sounds on the surface, these are signs to move to lower anger terrain and/or avoid loaded slopes.

Avalanche Discussion

 

Wind slabs that formed on Wednesday and Thursday are becoming stubborn and non reactive. Observations from Tam Rim showed active wind transport was still happening on Friday and I expect it to continue through Friday night and into Saturday to some extent. New snow coming in Friday night will add to the current windloading. Remember, wind can load a slope with snow many times deeper than the accumulated storm snowfall (see image below for example). 

While I am not including cornices on the problem list, watch for them at ridgtops. This time of year, the cornices are often thin and weak, and easily broken under a person's weight. Use caution when approacing ridgetops that you cannot see over to the other side. 

Storm slabs formed Wednesday and Thursday, are bonding to older snow and there were no reports of activity or cracking in the storm snow on Friday.

As we look ahead to Sunday, the weather models are suggesting we can expect up to an inch of water or more by the afteroon. This could destabilize the upper snowpack and lead to a wet slab and/or wet loose avalanche cycle.....more updates about that on Saturday night.

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