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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Thursday, December 8th 2016
Created: Dec 8th 5:37 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
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Special Announcement

Planning on taking an avalanche class? The Friends of the CNFAIC is offering two avalanche scholarships through the Rob Hammel fund. Both scholarships are for $500. One is for avalanche professionals and the other is open to anyone!  The deadline for both scholarships is Dec 15th! For more information click this link HERE


The Bottom Line

A MODERATE avalanche danger exists on all aspects above 2000’ where triggering an avalanche 1-2+’ thick is possible on slopes steeper than 35 degrees. Triggering an isolated wind slab avalanche is also possible today near ridgetops that have been loaded by winds over the past week. Below 2000' in the trees where the snow is loose and unconsolidated the avalanche danger remains LOW.

If headed to Summit Lake check out the Summit Lake Summary HERE.

***Out of area: Click HERE to check out an observation about a human triggered avalanche in the Anchorage Front Range on Dec. 5.


Primary Concern

A 1-2+’ slab sitting on top of a widespread layer of buried surface hoar continues to warrant caution in the alpine throughout Turnagain Pass. This layer was formed in mid November and was the cause of  dozens of human triggered avalanches over several weeks. Observers continue to find this layer on all aspects above 2000’ and many stability tests still show propagation potential.  However without any major weather factors adding stress to the snowpack this layer is becoming more stubborn and difficult to trigger with time. The places most suspect are large steep slopes (>35 degrees) that haven’t avalanched. Since we don’t have X-ray vision of the entire snowpack and evidence of natural avalanche activity was limited during several storms, uncertainty exists in terrain that hasn’t seen much traffic. The presence of surface hoar within the snowpack should be part of your slope choices today especially if you are venturing into steeper untracked areas. Consider the consequences of an avalanche before committing to a route and always use safe travel protocols. 

  • Expose one person at a time
  • Group up in safe zones
  • Have an escape route planned
  • Watch your partners and be aware of other groups around you

 The two photos below are examples of where the buried surface hoar continues to be reactive in test pits. Check out observations from Dec.6 at Sunburst and Dec.5 at Tincan.  


Secondary Concern

Several wind events over the last week have formed wind slabs near and below ridgetops on a variety of aspects.  Stiff supportable wind slabs formed in thin rocky areas may pop once you are out onto the slab. Be wary of hard over soft snow, hollow sounds and steep slopes with obvious deposition in the start zone.


Mountain Weather

Yesterday was overcast with low temperatures around 15F and highs around 23F. Winds were calm. No new precipitation was recorded in Turnagain Pass, and an inch of snow fell in Girdwood overnight. 

Today skies will be mostly sunny with a chance of light snow showers. Expect light ridgetop winds to be shifting from the East to a more Northerly direction and temperatures will be in the teens (F) to low 20F’s. 

A similar pattern is expected into the weekend with temperatures dipping back into the single digits and possibly cooler.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 21  19 
Summit Lake (1400') 16 
Alyeska Mid (1700')  18 .05 

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 20  ENE  17 
Seattle Ridge(2400') 23   ESE

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).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Dec 08, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedRain and snow have fallen in Turnagain Pass this week, but not enough to open for snowmachining. Continue to check back to this site for updates.
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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