Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You could find small wet or dry avalanches - or both - depending on the amount of new snow in the surrounding terrain. New snow on southerly aspects will warm with sun and rising temperatures. In other areas, wind drifted snow created unstable slabs that could take you by surprise. Pay attention to changing conditions throughout the day and adjust your plan as needed.

Problemi valanghivi

  • Loose Wet

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

    Clear skies and above freezing temperatures will open the door to wet loose avalanche activity. The biggest variable is the amount of fresh, loose snow available to warm up and then slide down.  You will see nothing on solar slopes with meager snow accumulations. If there are 4-6" or more you could see some semi-legitimate avalanches. Strong winds might keep the surface cool enough that it won't matter how much snow is on the slope above. 

    Rollerballs and other signs of instability are signs it’s time to pay attention to your exposure to steep terrain overhead. There is a really, really low chance that clouds and warm temperatures could create greenhouse conditions on shaded slopes. If this does happen be ready to see instability on all aspects.

    (1/27/2023)

    Very small wet loose avalanches and rollerballs running in new snow on. 

    Photo: Julz Holder - Grounding Truth

  • Wind Slabs

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

    Another 2-4” of new snow and wind made for another round of small but fresh wind slabs near and above treeline. On some slopes the slabs are forming on top of slightly faceted snow so they will take longer to bond. New slabs observed Wednesday were mostly small but they could still take you for a ride. Building winds in the afternoon will make for intense snow transport.

    If you trigger a slab it would likely be on a leeward slope just below ridgeline, or on a terrain feature like a convex rollover or gully wall. Look for blowing snow, changes in snow consistency, or visual clues like wind-scoured ridgelines to identify areas of wind slab.

    This photo illustrates observations that point toward wind slab on the other side of the ridge. Photo: Dallas Glass

Avalanche Discussion

Reports varied across West North. Observers near Anderson Butte found light winds and up to 6” of new snow that fell in the past two days. There were zero signs of instability other than light sluffing in steep terrain. At Heather Meadows, similar amounts of new snow were noted but strong winds had no problem redistributing it into fresh slabs. Ski cuts and other informal testing produced very easy results in wind loaded terrain.

Both areas have faceted snow grains at the new/old snow interface and also above the MLK crust buried 1-3’ deep. Neither is currently an issue but they are still layers to track going into future storms. Sun breaks were not enough to initiate signs of instability. It just stayed too cold through the day.

 

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