Turnagain Pass and Girdwood

Avalanche problems

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2

  The onslaught of spring snow continued yesterday, adding another 12 to 15" of new snow in Girdwood and Turnagain Pass. Conditions have been optimal for steady snowfall down to sea level with relatively light winds this week. 

  Weekly snowfall totals from weather stations at 1400' to 1800' elevation:

  • Girdwood: 7" water, 40" snow
  • Turnagain Pass: 4.4" water, 28" snow
  • Summit Lake: 1.5" water, 10" snow
  • Seward/Lost Lake: Snowfall weather station not operational

  All this new snow means human-triggered avalanches 1 to 2' deep are likely within the new snow. Avalanches breaking deeper in the new snow, up to 2 to 4' deep, are also possible. Especially in areas that received the heaviest snow totals this week like Girdwood, the north end of Turnagain Pass, and the north end of Seattle Ridge. We recommend a very cautious decision-making approach today since the snowpack has not had a chance to adapt to the heavy snow load. Sticking to lower angle terrain and being mindful of any steep slopes overhead are good ways to enjoy the new snow while giving the snowpack time to adjust.

  The dry new snow from this week is sitting on top of a wet and weak snowpack that had already started transitioning to springtime conditions before the weather decided to switch back to winter. This is a fairly unusual snowpack setup and we are uncertain about how likely the new snow is to bond to the old wet snow surface. If the sun pokes through the clouds this afternoon it could cause rapid changes to the new snow, potentially inducing a cycle of natural avalanches as the new snow from this week heats up. 

  With the snowpack at its deepest point in the season and lots of soft snow on the surface, tree wells are a significant hazard right now. We received a report of someone caught in a tree well in the Tincan Trees yesterday but luckily they were able to climb out on their own. Additional hazards to look out for include cornice fall along ridgelines and loose snow avalanches on steep slopeswhich could grow quite large due to the amount of new snow.  If winds pick up this afternoon wind slabs could form rapidly at upper elevations with lots of soft new snow available to be transported into fresh wind slabs. 

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  The added weight from the 4 to 7" of water this week is a major stressor on the buried weak layer of surface hoar that we have been dealing with since mid-February. This layer is now buried 2 to 4'+ deep. As far as we know, no new avalanches have occurred on this layer this week but the visibility has been terrible and we have received very limited observations. We still don't trust this layer and recommend you avoid traveling on or below steep terrain. This type of weak layer can produce very large avalanches without any warning signs even on slopes with many tracks. 

  

• 

  Glide Cracks

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  During the brief breaks in cloud cover this week we have observed continued glide avalanches releasing across the forecast zone. This is part of the normal spring shed cycle, but these avalanches are unpredictable and very difficult to manage with limited visibility. The best way to avoid them is to steer clear of steep terrain overhead. If visibility allows, try to keep an eye out for glide cracks opening up that are often a precursor to avalanches releasing.