Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Conditions will begin to change Saturday as a winter storm moves into the region.  Strong west winds will quickly build shallow wind slabs near and below ridgelines before sundown.  Take care while traveling near recently exposed hazards like open creeks, trees, and rocks. 

Problemi valanghivi

  • Wind Slabs

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

    Several inches of snow will accumulate in the Snoqualmie Pass area by sundown with strong west winds expected.  Winds may be strong enough to form fresh but shallow slabs further below ridgelines than usual. While these wind slabs will be small, they may be easy to trigger in areas where they bond poorly to the old snow surface.  Use small test slopes to test the bond of the new snow to old surfaces and watch for shooting cracks to help you gauge the problem. Steer around slopes where even a small avalanche could cause injury if you were pushed into rocks, trees, or over cliffs. 

    Shooting cracks are red flags of instability and should steer you to lower angled terrain or wind sheltered terrain.

    Photo: Robin Pendery

Avalanche Discussion

While this storm will deliver what we've all been waiting for, fresh snow, it will also further increase the avalanche danger Saturday night into Sunday. Plan ahead for poor visibility,  increasing snowfall and avalanche danger if you plan to stay out later Saturday afternoon or night.  And remember that it will take more than one storm to bury recently exposed trees, rocks, open creeks, etc .  

Several reports from the Alpental Valley on Friday detailed variable surface conditions and a few avalanches that occurred Thursday or Friday.  Several recent and very shallow natural slabs were noted in steep terrain below ridgelines.  On Friday, the sun exceeded forecast expectations and new and recent small loose wet and rollerballs were observed on sunny slopes. Thin surface crusts broke down and tree bombs released easily.  Wind sculpted surfaces could be found below ridgelines.  Surface crusts ranging from breakable to firm were observed on shadier aspects, with a few slick spots. One observation from the north side of Chair Peak found 5" of dry snow over the Valentine's day crust.  Observers this week found weak snow (small facets) under the Valentine's Day crust (4-5" down) rounding and strengthening over time.  While you can dig down further in the upper snowpack (1-1.5' around 5000') and find the more robust late January crust-facet combo, we don't expect avalanches down to this layer. 

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