Turnagain Pass and Girdwood

Problèmes avalancheux

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1–2

  Recent avalanches: It has been too cloudy to get a good inventory of recent avalanche activity, but we got a report yesterday of a few large natural avalanches south of Girdwood running to low elevation. We also got a report of several large avalanches occurring on the southern end of Turnagain Pass from Seattle Ridge to the Hope road. During last weeks storms, most avalanches were failing with only new snow, but a few looked deep enough to have failed on the December facets on Pastoral and Seattle Ridge.

  There is a break between storms today, but there are a variety of new snow problems that could be easy for a person to trigger today in the alpine. Easterly winds were blowing in the 30s and 40s mph on Sunburst yesterday. Above 2,500' where precipitation was falling as snow, fresh wind slabs were forming up to 2' deep. Winds aren't quite as strong today (20s mph expected), but strong enough to continue to form small new wind slabs up to 1' deep. With winds this strong, wind slabs could be anywhere in exposed areas, but especially under ridgelines and on steep rollovers. Keep in mind that triggering a new wind slab could be enough weight to trigger a much larger and more dangerous avalanche described below.

  Storm Slabs: Above 2,500' there is up to 1.5' of new snow in Girdwood and Turnagain Pass and storm slabs could be found in places sheltered from the wind. There are still chances a person could trigger one of these avalanches today that should be relatively small, but could still cause problems, especially if it occurs in a place where the snow could pile up or it carries you into rocks or trees. Quite a bit more water and snow fell in the Portage/Placer area during this storm (over 3' of new snow above rainline). There aren't very many places easily accessible to ride in those areas, but much larger avalanches could be triggered by a person and could run long distances if that's where you find yourself today.

  Wet loose: Temperatures are still warm this morning so surfaces may still be wet and wet loose avalanches may still occur. Watch for rollerballs to know a person could trigger one of these avalanches. 

  Water and snow totals from Monday 6am to Wednesday 6am:

  Location: Water: Snow above 2,500': Girdwood 1.7" 1.5 to 2' Portage 5.8" 4 to 5' Turnagain Pass 1.5" (most of this arrived since yesterday afternoon) 12 to 18" Summit Lake 0.4" 3 to 5" Seward 1.5" (most of this arrived since yesterday afternoon) 12 to 18"

   

   

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  2–3

  The storm yesterday added weight to the layer of weak facets that is buried 2 to 5' deep or more. It is becoming more difficult for a person to trigger an avalanche on this layer because it is buried so deep in many places, but it could still happen and the consequences could be serious. The following is what we know about deep slabs:

  • They are difficult to assess because normal snowpit tests don't work as well (the layer is too deep)
  • Tests give unreliable results
  • There is less feedback like whumpfing and shooting cracks
  • There can be many tracks on a slope before someone finds the thin spot and triggers the avalanche
  • They can be triggered remotely (from a flat slope below, on the side or above the avalanche)

  This problem can be completely avoided by choosing low angle or simple terrain and staying out from underneath large slopes above.