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Avalanche Advisory

Turnagain Area Avalanche Advisory
Friday, December 1st 2017 4:19 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is CONSIDERABLE near and above treeline (above 1000'). The recent storm has loaded a weak snowpack. Triggering a slab 1 - 2+ feet thick is likely on slopes steeper than 35 degrees. Remote triggered avalanches are possible. Cautious route-finding and conservative decision-making are essential today.  

Below 1000’ the avalanche danger is MODERATE where wet snow has cooled to form a breakable surface crust, but an avalanche from above is still possible.  

*Below Treeline: ICE CLIMBERS in Portage Valley: Avalanches today could be triggered remotely and propagate into higher terrain, sending debris over climbing routes.


 Show the Complete North American Avalanche Danger Scale
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Special Announcement

Motorized use on Turnagain Pass is closed due to insufficient snow cover.  Please see riding area status at the bottom of this page for the most up-to-date information.

Snowmachine Specific – Avalanche Safety and Lessons Learned at AMDS, December 5th @ 6:30 pm - 8:00 pm | FREE Join CNFAIC forecasters at Alaska Mining and Diving Supply for a talk about lessons learned from past avalanche events and get your brain in gear for avalanche season.

The CNFAIC Events Calendar is filling up with avalanche education opportunities. Check it out and find a class that is right for you! 

**For Hatcher Pass avalanche conditions see hpavalanche.org.

 


Avalanche Problem 1

The snowpack in the advisory area remains touchy and the hazard continues to be elevated due to the slab, 10-20" thick, sitting on a weak layer of faceted snow. This weak snow rests either on the ground or overlying a melt-freeze crust near the ground. This is not a set-up that will stabilize quickly, i.e. persistent slab. As the slab becomes more cohesive it may actually become more consequential. Yesterday the snowpack was "talkative" and observers noted many whumpfs, shooting cracks and some remotely triggered avalanches. These are all red flags.  The snowpack is clearly saying, "Hey, I am unstable!"  Step off of the skin track once in while and if you hear or feeling something let your group know. Triggering a slab on steep terrain remains likely, especially in leeward, wind loaded areas. Collapses (whumpfs) may propagate failure over large pieces of terrain and remotely triggering an avalanche is possible. This means you could trigger an avalanche from below while putting in a skin track. Eddies and Seattle Ridge both have this potential.  Many slopes have slid but that doesn't mean that the ones that haven't, won't. Steep slopes with cracking on them may still release. Be aware of runout distances and terrain traps. Overall it is still fairly shallow and rocky, and getting caught in an avalanche could take you for a very unpleasant ride. Staying on slopes less than 35 degrees will be crucial in terrain choices today. In addition pay attention to other groups in the area. Where you step may cause an avalanche in steeper terrain onto another party or you may expose yourself to another groups remote trigger. 

 Small avalanche remotely triggered yesterday by stepping off of the skin track. 

Avalanche triggered remotely by snowboarder on the adjacent slope. Photo: Mike Ausman

Avalanches in a gully feature, Tincan Trees. 

 

 


Avalanche Problem 2

In wind exposed areas of the alpine the new snow/old snow interface is more variable, and wind slabs may have formed in places without weak faceted snow underneath. These wind slabs are likely isolated, 1-2’ thick on leeward features below ridge tops. Wind slabs could be soft or hard depending on exposure to winds and if triggered could release a larger persistent slab lower down on the slope. Today is not the time to be pushing into steep terrain. Avoiding slopes greater than 35 degrees is recommended.

 

Avalanches off of CFR and the ridge below in leeward terrain. 


Mountain Weather

Yesterday was partly cloudy with light easterly winds that shifted to the west overnight. Temperatures were in the mid 20Fs to mid 30Fs during the day and cooled into the low 20Fs overnight. 

Today will be mostly sunny with highs in the upper 20Fs. Winds will be light and southerly. Overnight there is a chance of snow, 1-2". Temperatures will drop into the low 20Fs-high teens. 

Tomorrow will be mostly cloudy with snow showers. Another 1-2" is forecasted to fall. The storm track for Saturday looks to favor the Susitna Valley as it moves up Cook Inlet from the SW.  The next system on Sunday is a low with the favorable SE flow that could bring precipitation to the advisory area. The NWS forecast discussion this morning was less confident on the timing and details. Definitely stay tuned for precipitation amounts, wind speeds and temperatures... think cold thoughts. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33   0  0  18
Summit Lake (1400') 25  0  0 16 
Alyeska Mid (1700') 28  0  0

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  21  E 22 
Seattle Ridge(2400')  25 rimed   rimed rimed 

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: May 06, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20th
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: ClosedClosed as of May 7th. Happy summer, see ya when the snow flies!
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: ClosedClosed as of 4/27
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: ClosedClosed as of 4/27
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

Subscribe to the Turnagain Area Avalanche Advisory:

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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