Summit Lake

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  2–3

  Recent Avalanches: On Tuesday there was a widespread avalanche cycle in Girdwood, Turnagain Pass, and Portage Valley. Summit Lake also experienced a series of large avalanches occurring last week on Manitoba, Butch, and Ravens Ridge. While we are not sure, it looks like the December facets are responsible for these avalanches.  

  The December facets are still capable of triggering a large avalanche 1 to 3’ deep. The most telling evidence is that almost all observations in Summit Lake report large collapses including one on Manitoba Mtn yesterday. Collapses are extremely important red flags that are telling us that if we trigger a collapse on a slope that is steep enough, the slope would likely avalanche. 

  The safest option is to avoid traveling in avalanche terrain. This is a difficult problem to assess and even harder to tip toe around. A slope may avalanche even when there has been no red flags or concerning results in snow pits tests. Think about the consequences if the slope you intend to ride does slide and consider dialing back your backcountry objectives until conditions improve. 

  Wet Loose Avalanches: We are seeing wet loose avalanches after several days of above freezing temperatures and heavy amounts or rain saturating the snowpack. Overnight temperatures have started to cool below freezing which is a good thing, however this problem will remain a concern if there is not a hard crust on the surface and you are sinking into warm wet snow. These can start small and get larger quickly, entraining a lot of snow. They can be hard to escape and could pull you off cliffs, into terrain traps or into trees. 

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2

  There is a good chance of triggering a wind slab avalanche up to 1.5’ deep on wind loaded slopes in the alpine. As the storm made its exit yesterday an observation from Manitoba reported strong winds and blowing snow. While these may be on the smaller side the bigger concern is that triggering a wind slab avalanche may step down into the December facets causing a much more dangerous avalanche. 

  This type of problem is commonly found below ridgelines and in loaded gullies. Feeling for stiff snow and/or shooting cracks underneath you are obvious signs you are traveling on a wind slab.