Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Wed
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

You may still find firm wind-loaded pockets not only near ridges but also along mid-slope features. Look for drifts, cornices, and textured surfaces to help anticipate potential slabs. Steer around steep slopes with smooth pillow-like drifts.

Problemi valanghivi

  • Wind Slabs

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

    A human-triggered wind slab near Crystal Mt on Monday reminds us that these pockets of wind-loaded snow continue to linger around the West South zone. Two common themes repeatedly emerge about our current wind slab issue: 1. They occur not only near ridges but also along cross-loaded features mid-slope and 2. Hard slabs make predicting if and where these avalanches fail very difficult.

    Easterly winds on Monday formed a few very shallow fresh slabs on west aspects. However, these aren’t really the wind-loaded areas we’re concerned with. Older slabs from strong westerly winds this past week continue to hang around in some areas. While not all of these slopes may fail, any one of them could. Make sure to look for firm pillow-like drifts before committing to higher consequence slopes.

    (1/2/2023)

    A small human triggered winds slab in the Crystal Backcountry, 1-2ft deep and 40ft wide. W, 6300ft, HS-AS-D1-R2-U 

    Photo: Barrett Gray

Avalanche Discussion

Several days of quieter weather continue to allow the snowpack to gain strength and heal. As a result, the avalanche danger will slowly decrease. 

Observations from Mt Rainier NP, Crystal Mt, and White Pass on Monday highlighted a few key topics. 

  • New and old winds slabs exist including along cross-loaded mid-slope features
  • A breakable sun crust formed on steep southerly aspects
  • Soft settled snow is preserved on any slope that didn’t receive direct sunshine
  • A fresh crop of surface hoar formed at mid and lower elevations

Across the zone, 15-30 inches (35-75cm) of settled snow sits over the Christmas Crust. Shifting winds over the past few days significantly redistributed the snow on exposed slopes creating scoured icy surfaces and very firm deep drifts. 

Avalanche activity over the past few days has been limited to a few natural and human-triggered wind slabs as well as several small natural wet loose slides on New Year’s Day. Going forward, we are primarily interested in the upper snowpack above the generally stout Christmas Crust.

Regioni coperte