Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Tue
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

Snowfall and strong winds built new slabs of wind drifted snow over the weekend. Use lower angled, planar slopes to steer around steep terrain features with signs of recent wind loading. Avalanche danger could be greater during periods of intense snowfall that could affect some areas on Monday.

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs in steep convex or other unsupported terrain will still be hazard in backcountry travel. In addition, you may experience periods of greater danger - and even small natural avalanches - in areas that recieve heavy snowfall from the Puget Sound Convergence Zone. This could affect a very small portion of West Central but could put down up to 6" of new snow in a short period of time.

    Use scoured snow surfaces, drifts and other visual clues to hunt down day old wind slabs. Use simple observations like test slopes and hand pits to see how well bonded storm and wind slabs are to layers below. When in doubt just navigate around steep features where you suspect unstable snow. 

    (11/26/2022)

    Wind scoured and loaded terrain in close proximity at Stevens Pass .

    Photo: NWAC Public Obs

Avalanche Discussion

West Central recieved 8" to 12" of new snow by Sunday morning with a potentially bit more in favored locations. To the north, winds gusting to strong overnight eased off by the morning and minor wind transport was noted during the day. In the southern half of West Central, stronger winds were recorded through the day at Stevens and Snoqualmie Passes. Heavily scoured ridges were noted near treeline but good conditions were found in sheltered terrain.

Observers reported some, but not extensive, avalanche activity. Ski area mitigation work produced avalanches to D2 - mostly in wind loaded terrain. Small, shallow natural and human triggered avalanches were reported from wind sheltered areas. 

The new snow over the weekend fell on a strong snowpack of rounded grains, melt forms and crusts. Weak, faceted snow and surface hoar that developed during November’s drought didn’t likely survive in most areas due to temperature inversions, strong sun and alpine winds. Rain preceding snowfall on November 22nd probably soaked whatever surface hoar and facets remined. 

Upper elevation terrain and areas farther east in the zone (that experienced colder temperatures and less/no rain) may still have pockets of weak snow existing under new snow layers. There is no information from less traveled terrain near the Cascade crest or alpine terrain in general. Be prepared to look for and assess this layer if you travel in these areas.  

Despite the latest storm - and more snow on the way this week - it's still early season and the snowpack is still shallow. Many hazards remain including exposed or barely buried trees and rocks, open creeks and other rugged terrain features.  

Regioni coperte