Turnagain Pass and Girdwood

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–3

  Recent avalanches: We got reports yesterday of many new avalanches that occurred during the storms this week. The visibility was poor, but one report came from the north side of CFR Ridge on Tincan yesterday, April 11. See photo below of several storm slabs that occurred on the north side of Magnum. Another avalanche was noticed yesterday on the southwest side of Sunburst (where many people ride) that had some new snow on top indicating it may have happened within the last few days.

  The winds look like the biggest factor influencing the avalanche danger early in the day, but heavy snow is forecast as the day progresses, which will increase the chances for very large avalanches to occur naturally or be triggered by a person. There may be some anomalies today regarding wind slabs. They may be much larger than normal as there is an enormous amount of new snow available to be moved around and new snow will be falling.  A wind slab could trigger a much larger storm or persistent slab avalanche breaking 2 to 4' deep. Wind slabs also may be found lower in elevation than they normally are due to the strength of the wind that is forecast.

  With strong winds forecast today it should be easy to see where the wind is blowing snow into fresh slabs. Small test slopes within the treeline elevation band would be good places to see how fresh wind slabs are reacting and shooting cracks mean the snowpack has energy and needs some time to adjust.

  Large and unusual avalanches have occurred in past years with a similar snowpack set up. There is a large  2+ foot slab of new dry snow from the last week of storms sitting on weak grains that have been melting with warm spring temperatures. This is a precarious set up that brings a lot of uncertainty as to when it's breaking point will occur.

  Two days ago we received a report of someone stuck head first in a tree well in the Tincan Trees. Luckily, they were able to climb out, but this is a good reason to travel with a partner and keep an eye on each other. Cornices have been reaching their breaking point and will continue to fail through this storm and beyond as they warm up. Finally, loose snow avalanches on steep slopes are on the list of hazards today with a lot of dry new snow in the upper elevations.

   

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  The surface hoar that got buried on Valentine's Day is now up to 4' deep in Turnagain Pass. Today we transitioned from persistent slab to a deep persistent slab problem for a few reasons including the depth and behavior of this layer. Deep slab behavior includes difficult assessment (stability tests are unreliable because the layer is too deep), allowing multiple people or tracks on a slope before releasing, and remote trigger capability. This is a scary problem that is best managed by avoidance.

  

• 

  Glide Cracks

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  Glide avalanches continue to release across our forecast zones as the snowpack becomes weak as it melts. These avalanches are running into the treeline elevation band, so places that have been relatively safe this year may not be, as we go forward with the spring shed cycle. 

  Wet avalanches are less likely today with strong wind keeping surface conditions cool, but if the clouds come in later than expected watch for roller balls as the indicator the wet loose or wet slabs could be triggered naturally or by a person.