Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sat
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

Warming of steep, sunny slopes will be the main concern on Friday.  Stay off of slopes with wet, sticky snow during the middle of the day. On high shaded slopes near ridgelines, use caution near areas of firm or hollow sounding snow. Recently formed slabs may rest over weaker surfaces, and it may be possible to trigger an avalanche unexpectedly because of it. 

Problemi valanghivi

  • Loose Wet

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

    Strong sun will warm the snow surface quickly on steep, south facing slopes. Look for signs of warming instabilities such as rollerballs, or moist sticky snow overlying cooler, unconsolidated dry snow. Be cognizant of this before entering any steep, committing features where the consequences of getting caught in a small entrainment of wet snow could be higher. There may not be natural wet slides on Friday, but if you are riding in the wrong place at the wrong time, you could trigger one of these avalanches. If the snow surface is crusted over and refrozen, then the danger of triggering these slides has likely already passed. 

  • Wind Slabs

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

    Wind slabs are scattered about, in a pockety distribution around the compass. You may trigger one of these by surprise, as they likely rest over a layer of weak snow. Prior to the last storm, weak surfaces and surface hoar were widely distributed in the zone. Any recent slabs may continue to be reactive because of it. Wind slabs may become more connected and thicker as you ascend in elevation. Use surface textures and cornice formation as visual clues where slabs may be. Hollow sounding and firm or textured snow are other clues that wind transport has created slabs. 

    Look for signs of instability such as shooting cracks and whumphing as you travel.  If you see these signs of instability, dial back your terrain choices and stay off of steep features. In this case, be sure to avoid the obvious steep, wind loaded slopes, but also take into account unsupported, cross-loaded, and other midslope features. This is also a good time to dig lots of quick pits, looking for a thin grey stripe of buried surface hoar and to evaluate how any slabs are bonding. 

    (12/2/2020) Easterly winds continued to load NW aspects at the top of the Swath's start zone on Tuesday.

Avalanche Discussion

An observer in the Colchuck Lake area on Thursday found favorable travel conditions and no signs of instability. On Wednesday, observers in the Chiwaukum Range noticed plumes from ridgelines that indicated wind transported snow from south and east winds. Wind slabs were resting on a variety of surfaces, and although no avalanches were triggered, the structure of strong snow over weak snow existed. Before the last snowfall event, widespread surface hoar was found in the North Fork of the Teanaway on all aspects above 5000'. Other observers found surface hoar in places like the Chiwaukum Range as well. 

Snowpack height and coverage varies significantly across the area. Areas near the cascade crest have a substantially deeper snowpack than low elevations and further east. Use our list of weather stations to check how much snow is on the ground in various locations throughout the area.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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