Turnagain Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Sat, January 14th, 2017 - 7:00AM
Sun, January 15th, 2017 - 7:00AM
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

The avalanche danger is CONSIDERABLE  on upper elevation slopes. Human triggered wind slabs 1-2′ thick are likely on leeward terrain and natural avalanches are possible. In areas  unaffected by winds and receiving less snow  the danger will be  MODERATE  where small shallow storm slabs and sluffs in the new snow may be triggered on the steeper slopes.    Girdwood Valley received twice as much snow as Turnagain Pass.

Ice climbers and hikers:  In Portage Valley and other areas where climbing routes and trails sit under avalanche paths, be aware that debris from a naturally occurring slide above may run to these lower elevations.

Check out the Saturday Summit Lake Summary HERE.  

Special Announcements

Join us TODAY, Saturday, at  Hatcher Pass from 11am-1pm for a FREE rescue workshop!!  This event to brought to you by Hatcher Pass Avalanche Center, the CNFAIC, the Alaska Avalanche School, AAIC and hosted by the Hatcher Pass Snowriders Club.  More info  HERE.  

* Hatcher Pass continues to have  unstable conditions and received new snow,  check the Hatcher Pass advisory  HERE  if you are thinking of heading there this weekend.

Sat, January 14th, 2017
Above 2,500'
3 - Considerable
Avalanche risk
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

New snow (6+ inches at Turnagain and 12+ inches in Girdwood Valley) combined with moderate winds speeds ESE-ENE 15-25 (gusting to 40 mph) in the last 24 hrs have formed fresh, sensitive wind slabs on leeward slopes. Wind slabs may be 1-2′ thick. These slabs will be sitting on a variety of old surfaces and may not bond well. Slick wind crusts and soft facets covered most of the terrain prior to the storm. Places where the new snow landed on the slick crusts will be especially suspect. Look for new cornice formation, pillowed and drifted snow and cracking. Winds speeds have mellowed this morning but are expected to pick back up this afternoon. Watch for wind transporting snow and avoid travel underneath actively loading slopes as naturals will be possible. 

 Photos: National Avalanche Center 



Yesterday afternoon. 1.13.17, Snow starting to drift and crack. 


Avalanche Problem 2
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

In areas unaffected by wind new snow can still act as a slab especially in Girdwood where more snow fell. In addition temperatures warmed up overnight and the storm snow may be slightly upside down with heavier snow over lighter snow. The question during and right after a storm is “How well is the snow bonding to the old snow surface it landed on?” As noted above with the wind slabs, the storm snow landed on a variety of surfaces including slick wind crusts and may not initally bond well. Stepping off the skin track or jumping off your snowmachine to do quick hand pits will be a great tool for determining new snow depth and bonding. Also be on the lookout for loose snow avalanches in the steep terrain where the storm snow may not stick to old surfaces at all. Avoid terrain traps i.e. places where shallow avalanches could pile up more deeply and look for cracking.

As always practicing safe travel protocol is key:

1) Expose only one person at a time

2) Group up in safe zones 

3) Have an escape route planned 

4) Pay attention to other groups. This could be a busy holiday weekend! 

Additional Concern
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

Glide cracks have been slowing opening this week; though we have not seen/heard of any new cracks releasing. Keep an eye out for cracks, which is difficult with new snow and wind, and limit time underneath them. Main Bowl is one of the spots where glide cracks threaten terrain that is commonly traveled.

Sat, January 14th, 2017

Yesterday snow fell throughout the day with intensity picking up late in the afternoon. Winds were easterly 15-20 mph with gusts into the 30s and 40s. Temperatures were mostly in the 20Fs with a band of warm air at road level in Turnagain Pass in the 30Fs. Overall temperatures warmed slightly overnight and winds speeds dropped.  

This morning the skies are clearing on Turnagain but snow showers continue in Girdwood. These are forecasted to taper off to partly cloudy skies. Colder air will move in this afternoon with westerly winds to 15-25 mph. Temperatures will drop into the single digits tonight. The next storm system is forecasted to arrive tomorrow with another round of snow into Monday.  

PRECIPITATION 24-hour data (6am – 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 33    7  .6 40  
Summit Lake (1400′)  21  3 .4    14
Alyeska Mid (1700′)  28  13  1.4  35

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  22 ENE   18   40  
Seattle Ridge (2400′)  24  SE  15  29
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.