Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Wet snow is tricky and can produce wet avalanches long after the rain has stopped. The potential for these slides to grow very large has us holding a higher danger level until the snowpack has some time to adjust. These avalanches are not really a problem that you can manage, all you can do is choose safe travel routes that keep you well out of their way.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5

    The snowpack is still in a period of adjustment after rain made it to the tops of the peaks during this week's warm and wet weather. On Thursday, you should continue to think about wet avalanches anywhere you find unconsolidated wet snow on or near the surface. This includes above the rain/snow line. Wet snow may be more difficult to initiate a slide in, but once it gets moving it can grow large and destructive as it moves downhill. We expect most slides to be loose and initiate on steeper features over 35 degrees. However, if you find that slides are breaking off as a cohesive slab, be sure to dial it way back. Wet Slabs are not a problem you want to mess with. 

    (1/11/2022)

    Multiple paths on Granite Mountain produced wet avalanches on Tuesday morning (1/11) and again that evening, as elevated freezing levels and rain impacted the zone.

    Photo: John Stimberis

  • Glide Cracks

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    Glide avalanches are almost impossible to predict and can release long after the rain has stopped. These avalanches can grow very large since they often involve the entire season’s snowpack. They commonly occur on smooth rocky slopes, and large crevasse-like cracks (glide cracks) are the first indicator that these avalanches are possible. Locating glide cracks will be the easiest way to identify slopes capable of producing these avalanches on Thursday. Once you spot a crack, be sure to give that slope a wide berth to help minimize your exposure to these erratic avalanches.

    (1/12/2022)

    A glide avalanche that occurred on a smooth rocky slope on the night of 1/11. The entire season's snowpack failed, exposing rock as the bedsurface.

    Photo: Alpental Pro Patrol

Avalanche Discussion

As of Wednesday afternoon, the pass has received just under 4 inches of rain since Monday night. This load has stressed the snowpack and produced a variety of avalanches. We are still lacking information on the extent of the cycle, but WSDOT’s avalanche crew has relayed that Granite Mountain has naturaled twice in the past two days. Alpental Pro Patrol reported natural avalanches on rocky ledges and glide cracks opening up. 

On Thursday, we should see light snow at upper elevations and continued rain at lower elevations fizzle to end a wet and wild week. We expect snow accumulations to be minimal enough that new hazard won't develop. After so much rain, any new snow should bond well to the current surface. Maybe you’ll be able to find a small pocket of unstable wind drifted snow in isolated areas. Lower elevations should be generally well suited to handle additional rain on Thursday morning. Our concerns continue to be with the water that has already been introduced to the snowpack and further moisture tipping unusual avalanches such as Glides, cornice collapses, or Wet Slabs closer to the edge. 

Prior to this cycle, we had the opportunity to briefly get some information about very large (D3-D4) avalanches that occurred on January 6-7. We’ve now been through two very large loading events in which a lot of very large avalanches occurred. The snowpack has changed a lot in the past week, but uncertainty around these slides should still have your attention. Be patient and give the snowpack a bit more time to adjust to the rain before stepping into big slide paths or alpine terrain. These massive slides are unpredictable and the snowpack could have a few more surprises up its sleeve as we move toward high pressure.

Régions couvertes