Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Fresh snow and strong wind equal unstable new slabs. Use lower-angle terrain to bypass steep slopes that are collecting wind-drifted snow. You could see widespread instability and even a few natural slab avalanches by the afternoon. Monitor changing conditions and prepare to shift towards sheltered terrain.

Problemi valanghivi

  • Wind Slabs

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

    Expect an increase in wind speeds to build fresh wind slabs. Locations that received only a few inches of new snow on Friday will see a minimal increase in avalanche danger. But higher elevations and parts of the zone that saw deeper new snow could have legitimate wind slabs by the end of the day. Observations are limited but weather station data shows the Mountain Loop and Darrington likely received the most new snow in West Central. 

    Blowing and drifting snow will point the way toward the slopes where you are most likely to trigger a fresh wind slab. Changes in snow stiffness and scoured surfaces will can also help you identify slopes holding new wind slabs The best policy will be to simply steer around steep slopes where you observe active wind loading.

    (1/4/2023)

    Active wind transport should show you exactly which slopes are loading up. 

Avalanche Discussion

It was a quiet day with sunshine, cold temps, light winds, and some new snow.  Observers to the north reported scattered clouds that drifted in and out over the course of the day and were reported to hold warming in check.  In areas that saw more sun, you might find a thin crust on solar aspects. No natural avalanches from the latest storm or human-triggered wind slab avalanches were reported.

In neighboring zones the 4-6" of new snow wasn't quite enough to keep you off the frozen crust below. An observer in West North found deeper snow was above 5500' with drifts up to 2' deep just below ridgeline on north and east aspects. The new snow was also well bonded to the old and wet - but now frozen - snow surface in wind-loaded areas. Widespread dust-on-slick-crust conditions were reported from Snoqualmie Pass.

The snowpack below the crust consists of wet or moist melt form layers alternating with harder crusts. The existing snowpack (below the new snow) is more reminiscent of a strong, fully transitioned summer snowpack versus what we would see in a typical December.

The new snow barely conceals a number of creek holes, rocks, and even patches of bare ground that melted out in previous days. Old avalanche debris should also be on the checklist of non-avalanche hazards.

Regioni coperte