Bollettino valanghe

East Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Low-density and right-side-up snow is plentiful, but winds have drifted that snow into slabs you can trigger near and above treeline. Steer around unsupported slopes and those steeper than 35 degrees on lee aspects. On shaded slopes, consider examining a weaker MLK crust interface down for slab propagation before moving into higher consequence terrain.

Problemi valanghivi

  • Wind Slabs

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

    NWAC forecasts found deep and right-side-up snow (12" or more) on Darland Mountain on Wednesday. The snow was cohesionless in most terrain traveled EXCEPT where you find wind loading. Focus on these wind-loaded features for your slab hazard. Rippled snow surfaces (pictured) and pillow-like drifts are yellow flags. Shooting cracks and whumphs are red flags. You'll want to evaluate how deep the snow is in your terrain and how much drifting has occurred. We expect slabs to be found in the lee of ridgelines and on isolated mid-slope features. In more heavily wind-affected areas such as near high elevation ridgelines, wind slabs may be larger and more widespread. Given the depth of the snow, crowns would be 1-2 ft deep and difficult to manage on a large, steep slope. Continue to steer around wind loading on steep or unsupported slopes as the drifts need more time to gain strength after a major storm. In isolated areas, you may still be able to trigger a mid-storm instability (see image gallery), but the same terrain travel advice applies.

    (2/8/2023)

    Wind-rippled snow showing loading and transport near treeline.

    Photo: Joe Dellaporta

  • Loose Wet

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

    After a chilly start, temperatures will rise into the 30s with clouds giving way to plenty of sunshine on Thursday. As the sun gets higher and temperatures warm. expect rollerballs and a transition to small wet loose avalanches. Navigate away from steep slopes receiving sunshine, especially if the slopes are above you. We don't expect these will entrain the full 12" storm snow, but if you see large avalanches occurring, this problem is more serious than forecast and you should give a wide birth to all steep, open slopes on SW-S-SE aspects.

Avalanche Discussion

A lot of folks were testing a variety of slopes on Wednesday, with no signs of reactivity and slabs limited to wind-loaded pockets. However, forecasters found a weak interface around 1.5 ft down at the MLK crust on a NW aspect (photo in the snowpit image). The interface produced some reactivity on compression, but did not propagate. Further evaluation of this layer may be necessary, so consider digging if you plan to venture onto larger shaded aspects near or above treeline. The same layer produced no results on an E aspect. 

Tuesday's storm was the since the wet MLK storm and has brought winter back in a major way to the ES zone. Deeper snow brings with it the potential for larger and more consequential avalanches, so it is prudent to adjust your mindset accordingly.

If you get out into the East-South, please let us know by submitting an observation!

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