Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Slabs of wind-drifted snow should be on your radar tomorrow. Look for areas of wind loading from the past storm and also with continued moderate winds. Warmer temperatures and more sunshine are in store so there is a greater chance of seeing wet avalanches on southern aspects.  Unusual avalanches reported from adjacent zones warrant extra caution in mid and upper elevation wind loaded terrain.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2.5

    Three different human triggered avalanches were reported In West North from Canyon Creek and Schriebers Meadow (click for observation) on the south side of Baker. These avalanches were large, surprising, and quite dangerous. They are not typical wind slabs but they occurred in obviously wind loaded terrain. They are not everywhere but they are in enough places to warrant additional caution. The layer thought to be responsible for these avalanches - a layer of facets combined with a melt freeze crust - is the same one suspected as behind the widespread avalanche cycle during the storm. In some places, a layer of graupel is found just above the facets.

    In addition to these big ones, numerous rider and skier triggered avalanches were reported from most areas on the west slopes. They were smaller and shallower but still could take you for a ride or bury you in a terrain trap below.  

    The safest bet for Thursday might just be to just stay in lower angle, wind sheltered terrain until the next round of precipitation, warming, and wind runs its course - and the pattern of recent avalanche activity is better understood. 

     

    (2/8/2023)

    Large snowmobile triggered avalache at Schriebers on the south side of Baker. East aspect at 6300'. Triggered from red circle. No one was caught in this one.

    Photo: NWAC Public Obs

Avalanche Discussion

In addition to small and large slab avalanches in wind loaded terrain, light to moderate precipitation at questionable snow levels are additional factors for Thursday. Rising snow levels could produce rain at low and maybe mid elevations and wet loose avalanche activity to go along with it. Keep track of changes in the weather and adjust your plan as needed. Give slopes with fresh rollers or other signs of warming or rain effect plenty of space. 

Convergence zone enhanced snowfall put down another 8-12" across West Central by Wednesday morning. No observations were submitted from this zone. Observers in Steven and Snoqualmie Pass found signs of a natural avalanche cycle and  storm and wind slabs becoming better bonded and less reactive throughout the day. In Snoqualmie rain or very wet snow persisted through the storm to about 4500' with minimal snow accumulation below this elevation.

The current avalanche picture is tricky and information is sparse about the precise layering and other snowpack and terrain factors. Some areas that saw widespread natural avalanche activity might have had weak layering cleaned out of steep terrain. Other places that saw less of an avalanche cycle might have numerous slabs just waiting for a human trigger to tip the scale. Yet others may never have had weak layering to begin with. The easiest way to reduce uncertainty is to limit travel in steep terrain.

 

 

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