Seward and Lost Lake

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  On Thursday, Andrew found the buried surface hoar about 2' deep on Mt. Eva at 3,100'. It was stubborn to initiate in stability tests but it failed with a lot of energy. We haven't seen as many avalanches on this weak layer in the Seward area and snowpit information tells us it may be more stubborn to trigger here than it is in Turnagain Pass. We also have less information in the Seward zone so that increases our uncertainty about this problem in this area. The danger rating is MODERATE in Seward for this problem, which means we think the likelihood of triggering this type of avalanche is lower than it is in Turnagain Pass, but we still think there are chances a person could trigger a large avalanche on this layer and the consequences could be severe. 

  One other consideration is that tracks already on a slope don't mean it's safe. Tracks can tend to increase our trust in a slope, but this particular weak layer has proven itself to be unreliable and unusually dangerous in Turnagain Pass.  Many human-triggered avalanches in Turnagain Pass have been triggered after there are many tracks on the slope. If venturing into steeper terrain, look for slopes without consequenses like rocks or trees. Also, ensure that the slope fans out at the bottom with no gully features that could allow debris to pile up.

  

• 

  Glide Cracks

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  Large temperature swings this week have expedited the transition to a spring snowpack. This transition will continue for many weeks and brings a great deal of uncertainty. There are many factors that affect the timing of warming and melt water infiltrating a snowpack, which leads to wet snow problems. This makes forecasting the timing of these problems difficult and an extra margin of safety is a good idea. Because we have this especially dangerous weak layer described in problem 1, the safest option is to stick to low angle slopes as our extra margin. An extra margin of safety can also include being critical of safe spots, ensuring we are watching partners, and choosing slopes without consequences.

  Wet loose avalanches have been releasing naturally as the snow heats up in the afternoon. The forecast is for the clouds to clear out today, but this problem may occur even if some high clouds stick around. Roller balls are the indicator that wet loose avalanches could be triggered by a person. Wet snow is heavy and difficult to escape especially when a lot of it becomes entrained. 

  Cornice fall has been occurring naturally as well with warming temperatures. In some places (most recently in Portage above the Shakespeare Glacier) these large triggers have produced slab avalanches beneath. Keep an eye on cornices if you are passing beneath and give them plenty of room on the ridge. 

  Wind slab - North winds have been elevated since the early morning hours of Friday, March 28. There are good chances small new wind slabs are forming in the upper elevations that could be up to 1' deep or more depending on wind speed and how much snow is moving. Watch for blowing snow and avoid places where it is being deposited. Wind slabs may feel hollow because they are forming a slab of stiff snow over softer snow and a shooting crack means the snowpack needs time to adjust.