Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
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

Small, new wind slabs at the highest elevations are the main concern Thursday. Be on the lookout for and bypass steep terrain with pockets of recently wind drifted snow. You are most likely to find a fresh slab if your route takes you into alpine terrain.

Problemi valanghivi

  • Wind Slabs

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

    Strengthening winds in the afternoon should transport snow onto leeward terrain features. Slabs that do form should be easy to identify - observe the direction of blowing snow and take note of where it lands. 

    Widespread wind transport and slab formation are not expected at treeline - if you see otherwise consider avalanche danger a notch higher and take appropriate measures.

    If you end up in wind loaded terrain just navigate around convex or other steep features where you are more likely to find a slab. Wind slabs are easier to trigger during or immediately after active transport and loading periods.

    Use visual clues to help you identify wind loaded slopes. In this case, cornices often are a great indicator of a wind drifted slope beneath. 

    Photo: Joe Dellaporta

Avalanche Discussion

A shot of sun and warm morning temperatures could keep signs of instability in play until clouds thicken. The likelihood is low, but don't completely discount the idea of seeing a small avalanche or cornice failure (photo). Give a wide berth to steep slopes where you observe rollerballs, pinwheels, or small avalanches.

Observers reported little in the way of wet loose avalanche activity in the Hwy 542 corridor. Plenty of rollers and other signs of instability were noted, but solar aspects only produced a few small avalanches. The current batch of wind slabs was thought to be dead in the water - but a single cornice triggered slab avalanche (observation) in very steep above treeline terrain was reported late Wednesday. No other slab avalanches were reported the last two days .

Cold snow and good riding conditions were preserved on aspects not getting direct sun. Very steep terrain produced minor sluffing. A crust should top solar aspects on Thursday morning.

Below the surface, 1-3’ of recent snow rests on the stout rain crust buried in mid-January. Interfaces between these newer layers have not produced avalanches or positive test results in a few days. Under the rain crust, there are layers of rounded grains interspersed with crusts from rain events this winter. Deeper weak layers are considered dormant but may wake up in the spring with extensive warming or very, very heavy loads,.

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