Bollettino valanghe

West 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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In sintesi

Warming and strong solar radiation will raise concern for wet loose avalanches and cornice fall. Ease into upper elevation terrain slowly, and steer around steep sun-exposed slopes during the heat of the day.

Problemi valanghivi

  • Loose Wet

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

    Loose wet avalanche activity has been ongoing during the past week during periods of sunny skies and warming afternoon temperatures. This pattern will continue Friday. The sun will first need to break down a melt-freeze crust on solar aspects. By the time this happens, snow surfaces should be wet, weak, and primed for loose wet avalanches. Monitor changing conditions throughout the day, and keep your return routes in mind. The loose wet hazard will be limited early morning and where you find firm and frozen snow surfaces. The best chance for loose wet avalanches will be during the afternoon, especially on upper elevation south and west aspects. Watch for snow shedding from trees and rocks, and rollerballs and pinwheels following soon after. Although most loose wet avalanches are expected to be small, some could grow large and run far downslope. Steer around steep terrain with evidence of wet snow and move to shaded or lower angled slopes to avoid the problem.  

    (3/11/2021) Large pinwheels below treeline near Mt. Pilchuck

Avalanche Discussion

From March 4-7, at least 1ft of new snow accumulated above 4000ft throughout the West Central Zone. Beautiful weather arrived Thursday, and observers on Mt. Pilchuck reported cold snow on northerly upper elevation slopes and soft, smooth, corn-like conditions on solar aspects by mid-day. Rounds of loose wet avalanche activity occurred earlier in the week, and more is left to flush out with continued sunny, warm weather set for Friday. Deposits of wind-blown snow from last weekend's storm are generally settling and stabilizing but you may still be able to trigger a lingering wind slab in isolated alpine areas. Continue to approach upper elevation terrain cautiously, and give cornices a wide berth. These unpredictable features are large and overbuilt and can break further back than you may expect or fall onto slopes below acting as huge triggers.

Deep persistent slab avalanches are dormant and unlikely, but the snowpack structure can still be found. The Mid-January PWL is now 10ft below the snow surface and gaining strength. The last deep slab avalanches in this zone likely occurred around February 25 with suspected avalanches in adjacent zones as recently as March 1-3. Major warming events later in spring and summer could trigger further rounds of avalanches on this layer. Keep in mind the consequences of these massive avalanches and give yourself an extra margin of terrain in large avalanche paths.

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.

Regioni coperte