Summit Lake

Lawinenprobleme

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Likely

  Größe

  2–3

  Recent avalanches: January 16th-17th marked the peak of avalanche activity across all forecast zones, with dozens of natural and human-triggered avalanches recorded from Anchorage to Seward.  The Summit Lake zone was no exception and continues to show signs of large whumpfing in the snowpack as recently as Tuesday.  Yesterday, there was a (likely) remote-triggered avalanche on the popular west face of Sunburst that took out several sets of older ski tracks.

  Persistent slab avalanches are responsible for the majority of accidents and fatalities among backcountry users.  Tracking and identifying weak layers isn't the difficult part.  The crust/ facet combo we're dealing with is well documented and easy to identify, particularly in the 1,500 to 2,500' range, where it shows up as a solid grey line 1 to 3' below the surface.  Above ~ 2,500', where the crust begins to thin and disappear, we still have very weak snow causing large, connected avalanches.  Predicting when and where backcountry users will affect these weak layers is the part that proves challenging, particularly the further we get from a loading event.  John was still finding a very reactive snowpack (large collapses that shook branches) during his travels in the Summit Lake zone on Tuesday; however, shooting cracks or whumpfing in the snow may not present the obvious red flags they did a week ago. 

  Fortunately, there are some ways to mitigate this avalanche problem, as this is likely to be a concern for some time.  Sticking to low-angle (simple) terrain with no overhead hazard is a good strategy.  This means conservative skin tracks and parking sleds well away from the toe of slopes.  If you do find yourself stepping into more complex terrain, maintaining safe travel habits will be key.  This means spacing out, exposing only one person at a time to avalanche terrain, watching your partners, and grouping up in true islands of safety.  Be rescue-ready and consider the consequences if a slope does slide, e.g., terrain traps.

  Wind Slabs: Forecast zones saw moderate to strong winds on Sunday/Monday, moving a significant amount of snow around, particularly in the upper elevations.  It's possible someone could trigger a stubborn wind slab today with the potential to step down into deeper layers mentioned above.