East Slopes Central

Problemi valanghivi

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Likely

  Dimensione

  1–2

  Light snow overnight on Thursday will intensify on Friday, and snowfall will increase throughout the day. This warm, wet storm will override an unusually cold airmass leading to some uncertainty with precipitation type. We expect the precipitation to stay as snow on the east slopes of the Cascades. However, it wouldn't be a total surprise if we had a changeover to sleet, freezing rain, or just plain rain in areas near the Cascade Crest. Even if we see all snow during this storm, the warming temperatures will result in sensitive storm slabs. Despite the less-than-spectacular precipitation totals forecasted for the East Central Zone, various weak snow surfaces and deeper weak layers make this a particularly dangerous situation with significant uncertainty. Locations in the western portion of the zone may see warmer temperatures and higher total water amounts out of this storm, potentially resulting in larger avalanches. Avoid steep slopes on Friday and be cognisant of steep features above terrain traps such as creeks, holes, or ravines where you could be buried deeply by even a small avalanche. 

  It will be a great day to identify red flag signs of instability, such as recent avalanches or shooting cracks while traveling on low angle slopes. If you observe a change from snow to rain, know that natural avalanches may be increasingly likely, and you should also avoid traveling under steep slopes. 

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  1.5–2.5

  Observations came in on Wednesday from many areas in the mountains surrounding Leavenworth of touchy avalanche conditions, with slabs failing on weak snow on the 12/18 and 12/8 interfaces. This storm will begin to stress these older interfaces and more deeply buried weak layers. Avalanches starting in the new snow storm on Friday could step down to these persistent weak layers. Large, weak faceted crystals from mid-Novemeber 11/22) are still lurking near the base of the snowpack in many locations. While there hasn't been any recent avalanche activity on this layer, persistent weak layers are tricky. There is a possibility for additional stress from new snow to reawaken this deeply buried weak layer, resulting in large avalanches that run on the ground.

  Persistent slab avalanches can propagate farther than you anticipate, and you could trigger them from lower angle slopes adjacent to steep terrain. Hearing loud whumping collapses is a sign that these layers have the potential to produce an avalanche. It will be best to avoid traveling on steep terrain until these weak, sugary snow layers adjust to the new load.