Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

As you ascend in elevation, keep an eye out for textured surfaces or fresh drifts as indicators that Wind Slabs could exist in nearby terrain. They’ll be more likely on the leeward side of ridgelines or the base of cliffs. If you suspect a feature to be wind-loaded, simply steer around it.

Problemi valanghivi

  • Wind Slabs

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

    We’re expecting just enough snow and wind at mid to upper elevations that you could encounter some shallow Wind Slabs on lee slopes on Monday. Look for actively blowing snow or fresh drifts that look “fat” in comparison to the surrounding terrain to help identify wind-loaded features to avoid. They’ll be more likely near ridgelines and rocky terrain or on convex rollovers. 

    (3/17/2023)

    Snow was sifted to the base of cliffs by light easterly winds on 3/17 in the neighboring Snoqualmie Pass zone. Wind Slabs like to develop near rocky terrain.

    Photo: Andy Harrington

Avalanche Discussion

It was a generally warm and sunny weekend around the West Central zone with temperatures soaring into the 40s and even 50s at NWAC weather stations in neighboring zones. On Saturday, backcountry travelers on Palmer Mountain reported Wet Loose avalanche activity on upper-elevation slopes in the sunshine. In neighboring zones such as the West North, Stevens Pass, and Snoqualmie Pass, similar observations poured in. This has us believing that fairly widespread Wet Loose avalanche activity occurred on most aspects except true northerlies. As temperatures continue to cool with our incoming storm wave, expect these warm and wet surfaces to lock up and become a new crust. On those shaded aspects, we suspect that well-settled powder with, in places, weak surface hoar exists. On Monday, you should dig with your hand to take a look at how well the new snow has bonded to the underlying surface wherever you are out playing. 

We suspect the majority of avalanche activity to involve the new storm snow, which could run far and fast on the underlying crust if it is poorly bonded. If overlaying the surface hoar on northerly aspects, slides could break widely or even wrap terrain features. At the lowest elevations, expect precipitation to be liquid, which could result in some wet avalanche activity such as rollerballs or Wet Loose slides.

The outlier event could be an isolated Glide avalanche. After a weekend of warm and mostly sunny weather, Glide slopes have reportedly been on the move in the neighboring West North and Snoqualmie Pass zones. These unpredictable avalanches aren't a problem you want to mess with. If you notice large crevasse-like cracks on a slope, be sure to give it a wide berth.

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