Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, January 21st 2018 5:31 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

MODERATE avalanche danger exists on all aspects above 2,500' for triggering a very large slab avalanche between 3 and 8+' thick. These dangerous avalanches are more likely to be found at the high elevations, above 3,000' and though tough to trigger, have very high consequences. Additionally, loose snow sluffs are getting faster and larger by the day and be aware of cornice falls along ridgelines. There is a LOW danger below 2,500' where triggering an avalanche is unlikely.

 Show the Complete North American Avalanche Danger Scale
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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1

Deep Persistent Slabs

Almost Certain
Very Likely


Very Large


It has been 4 days since a very warm storm slammed into our area dropping inches of rain up to 2,500'-3,000' and several feet of snow above this. Since then, cold temperatures have cemented the wet snow into place and locked up any slab avalanche problem below 2,500' and 3,000' in areas. Therefore, our main concern lies at elevations above this where a 'deep persistent slab' problem exists. On these upper elevation slopes, a dense hard slab is sitting on a variety of weak layers in the mid pack (buried surface hoar) and old November facets near the ground. Triggering a deep slab will be more and more difficult as the days pass, but still possible. The most likely spots to trigger them are thin areas in the snow cover, often near rocks, or where the slope rolls over. High peaks, that see a lot of wind, can also be thinner and more likely to find a deep slab.

If you are headed out today, and the skies stay clear enough for easy travel above treeline, keep these points in mind:

-  This is 'low probability, high consequence' situation - often refered to a 'Scary Moderate' avalanche danger
-  Several tracks may be on a slope before someone finds a trigger spot
Obvious signs of instability are not likely to been seen (such as whumpfing and cracking)
-  Remote triggering is possible 
-  This issue can simply be avoided by sticking to terrain below 3000’ (which is a good portion of terrain at Turnagain) or choosing low-consequence terrain in the alpine.

 Photo: Old cornice fall and avalanche from 1/16 near the Seattle Headwall region at 3,300'. Steep upper elevation slopes that have not slid are the ones most suspect for triggering a large slab avalanche.


Avalanche Problem 2

Dry Loose

Almost Certain
Very Likely


Very Large


Loose snow sluffs are rocketing down steep slopes as this cold weather continues to loosen and facet the surface snow. If choosing large steep terrain, watch your sluff. At mid elevations where 4-8" of loose snow sits over a hard crust, sluffs are still likely and although not deep, will run quite far. 

Additional Concern


Cornices have grown with the last storms, many have fallen, yet many have not. As always, give these features a wide berth and remember they can break further back than expected. A cornice fall at the high elevations could trigger a large avalanche on the slope below.

Mountain Weather

Mostly sunny skies with thick mid-elevation and valley fog filled the area yesterday. Temperatures were chilly, generally in the teens at all elevations. Overnight temperatures have dropped into the single digits in many valley bottoms and mid-elevation locations. Winds over the past 24-hours have been light and variable.

Today, we should see a slow climb in temperatures as light Easterly flow brings clouds and a chance for snowfall. By late today, an inch of snow is possible at all elevations (including sea level). Overnight, another 2-4" is possible, again at all elevations. Temperatures are slated to climb into the upper teens at most locations. Winds are expected to be 5-10mph from the Northeast.

Tomorrow, Monday, light snowfall is possible, but little accumulation is expected. Skies also may clear a bit. Winds look to remain light and temperatures will be on a downward trend. 


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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 12  54 
Summit Lake (1400') 10  15 
Alyeska Mid (1700') 15   43


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 14  NE  12 
Seattle Ridge(2400') 10   N calm  16 

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: Mar 15, 2018 )

Glacier District
Johnson Pass: Open
Placer River: OpenPlease avoid private property and AKRR job site at Luebner Lake. Cross railroad tracks if needed, do not ride down tracks, it is illegal.
Skookum Drainage: OpenCross railroad tracks if needed, do not ride down tracks, it is illegal. FYI, Skookum drainage closes to Snowmachines on 4/1 as per the Chugach NF plan.
Turnagain Pass: Open
Twentymile: OpenCross railroad tracks at designated spot as you leave the parking area.
Seward District
Carter Lake: Open
Lost Lake Trail: Open
Primrose Trail: Open
Resurrection Pass Trail: OpenResurrection Pass trail is open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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.

If you have comments or questions regarding CNFAIC operations or winter recreation management, please email
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