Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

The last day of rain is going out with a bang, with two inches expected Thursday. We don't think there will be many avalanches still running, yet wouldn't be surprised if a very large avalanche unexpectedly releases. Surfaces will quickly freeze from Saturday, but in the meantime, steer around steep slopes and avoid or travel quickly through lower-angle terrain beneath large avalanche paths.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Our wet-snow avalanche concerns are shifting toward a low-likelihood/high-consequence scenario, as we think many avalanches have already run their course during this unprecedented soggy period. It still wouldn't be unexpected, however, for a large avalanche to release, ripping all the way down a sneaky gully to lower elevations on Friday. 

    Expect any kind of wet-snow avalanche if you get out on Friday. You might be able to trigger small wet loose avalanches. They might step down to much larger and more destructive slabs on large slopes. Glide cracks are opening up. Beware cornice fall, and snow chunks shedding from steep rock slopes. 

    Avoid steep terrain. Given how much uncertainty exists during this unusual period, consider steering around the bottom of large avalanche paths, where avalanches run and stop- or at least traveling quickly through them. 

  • Wind Slabs

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

    Temperatures are finally starting to cool, and we're finding it hard to believe but we might get a foot or more of snow at upper elevations. If you make it up there, you'd be most likely to trigger an avalanche where wind deposits snow into larger drifts. 

    Steer clear of wind-loaded slabs on steep slopes. They might not be big enough to kill you, but if you're above a terrain trap, the consequences are magnified if you're caught.

    Example photo: Small wind slabs deposits could fracture and release at upper elevations on Friday. They may not be very large, but don't let one catch you in high consequence terrain. Note the textured surface where this slab released. 

    Photo: Adam Ü

Avalanche Discussion

Observers and forecasters in the West North (observation), Stevens Pass (observation), and Snoqualmie (observation) zones on Wednesday and Thursday all reported saturated snow surfaces, and moist snow as far down as they could dig. Avalanches ranging from wet loose, glide, and wet slab, plus shed-style failures, have all been reported.  Several have been seen in the West Central zone as well from the Hwy 2 corridor. 

As of Thursday evening, Snotel sites in the southern half of the zone received over 8 inches of rain since Monday morning. Anywhere from 3 to 7 inches was recorded further north. Last week's storm deposited about 2ft of new snow in the northern half, but closer to 4ft in the south. Snow heights diminished by almost 2ft in the zone during the rainy period. Avalanches could fail within the newer layer, or even beneath it now. 

Rapid cooling is finally greeting us Friday night, and we expect previously wet, soggy surfaces to freeze by Saturday. They could be solid underfoot, or maybe you could still punch through the crust on Saturday. Avalanche likelihood will further decrease as the crust locks the surface, but given the massive amount of rain that's still trickling through the snowpack, for at least one more day, we wouldn't be surprised if a very large natural avalanche still unexpectedly releases, completely disregarding the superficial surface crust. 

Monday morning brought the first rain and warming, and a flurry of wet, loose avalanches followed. Since then, we expect that there were more wet avalanche cycles, but don't have any confirmation. Travel conditions are challenging, with wet, heavy snow, open creek holes, and other hazards that increase the risk of injury and complicate travel during this soggy period. Lower elevation snowpacks are rapidly melting, and aside from large avalanches coming down from higher elevations, danger at lower elevations is decreasing. 

Regioni coperte