Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Wed
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

Pay attention to changes in wind direction - and where the wind is drifting snow and building new slabs. Bypass steep terrain where you identify recently wind-drifted snow to avoid triggering an avalanche. Generally safe conditions are found in sheltered terrain.

Problemi valanghivi

  • Wind Slabs

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

    Active wind transport was reported today and will continue through Tuesday. A midday shift in wind direction will change up the pattern of wind loading, especially farther east in the zone. Look for wind slabs on aspects where you might not normally see them. Blowing and drifting snow will be the primary observation to figure out where the freshest, easiest-to-trigger slabs are building. Wind-affected snow surfaces and other clues can help identify the loading pattern if winds die down.

    The weak storm headed our way has more huff than fluff with only a few inches of new snow expected by Wednesday. With that in mind, the danger from wind slabs should mostly depend on how much light snow is on the surface. Deeper new snow equals the potential for bigger slabs. Most of the new wind slabs should be small and shallow given many areas only have 4" of new snow. But larger ones could form in areas that saw more new snow with the latest storm. 

     

    (3/12/2022)

    Look for shallow wind slabs on leeward aspects on Tuesday. The small cornice features right of the crown are indicators that this slope could be wind loaded

    Photo: Pete Durr- USFS

Avalanche Discussion

Observations on New Year’s Day varied depending on location within West North. Strong winds and wind-transported snow were observed on Ptarmigan Ridge in the Baker BC, while calmer conditions were found north of Hwy 542. No older wind slabs from Friday’s storm were found and no new slab avalanches were reported. 

Small dry loose avalanches were triggered in steep terrain. A solid overnight refreeze and occasional high clouds kept warming at bay despite full sun in the morning. The fresh snow was a much-needed change and good riding conditions were the main observation of the day. Surface hoar was found topping the snowpack on all aspects Monday morning but was knocked down and dispersed in areas that saw higher afternoon wind speeds.

Snowpits at mid and upper elevations have repeatedly shown a well-consolidated snowpack with no layers of concern. Below the new snow, all layers are well bonded and consist of moist crusts, melt forms, or rounded grains. 

On Sunday, there was 4-12” of dry new snow at mid and upper-elevations. It was right-side-up and well-bonded to the old wet snow surface. Heather Meadows picked up a total of 1.35” of precipitation from the latest storm. Most other weather stations in West North picked up about half that amount. The Martin Ridge Snotel above Baker Lake had 1.0" of precipitation which indicates the south side of Mt Baker/Schriebers likely saw significant snowfall up high. 

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