Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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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 can trigger an avalanche in areas where the wind has deposited new snow into fresh slabs. Due to high wind speeds, you may find these wind drifts forming further down slopes than usual. As you climb in elevation, give steep wind-loaded slopes some space. 

 

Problemi valanghivi

  • Wind Slabs

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

    Light snowfall accompanied by strong  NW winds will create a fresh crop of  shallow wind slabs. Winds will be cranking, so don’t be surprised if you find these slabs forming well below treeline or further down slopes than usual. These slabs will likely stay on the shallower side, but as the day progresses you may find these drifts getting deeper, especially in those above treeline areas. 

    Once you lose the wind, you lose the problem.  However, that will be easier said than done, since it will likely be in your face at the trailhead. So use visual clues to help you identify slopes of concern. Keep an eye out for sharp cornices forming, fresh pillow-like slabs, or blowing snow. Take a big step back and avoid steep terrain if you notice shooting cracks or see slabs sliding easily on smaller slopes. 

    (1/17/2023)

    Shooting cracks - a red flag that should not be ignored.  Avoid wind loaded slopes if you notice signs like this. 

    Photo: Joe Dellaporta

Avalanche Discussion

The East-South will be a little late to join the precipitation party. Monday should bring light to moderate snowfall and strong to extreme ridgeline winds. We’ll be getting the biggest punch of precipitation arriving Monday night and into Tuesday. So with that, look for a sharp rise in avalanche danger. 

As we move into this stormier regime the big question mark will be how the new load bonds with the old snow surface. Observers have reported weak, faceting snow on northerly aspects.  So as new snow piles up, be sure to check how its bonding with the old snow interface. Use small test slopes or hand pits to gauge how easily the snow slides. 

On Friday an observer in the American Ridge area reported finding good cold snow on east facing terrain, faceting snow in the shade,  and a sun crust on solar slopes that extended up to ridgetop.  At higher elevations they noticed winds drifting any remaining soft snow. Check out their full observation here. 

The MLK crust remains a prominent marker in the upper snowpack. Last Wednesday, NWAC forecaster Joe Dellaporta found this layer 1-2' below the snow surface. While some weak snow is associated with the crust, snowpack tests where they traveled did not produce propagating test results. The weakest snow associated with this interface (rounding facets)was on shaded aspects (NW-N-NE) above 6500 ft.

Let us know what you see by submitting a public observation. 

 

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