Turnagain Area Avalanche Advisory
Saturday, January 26th 2013 6:13 am by Kevin Wright
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

A MODERATE danger lingers above treeline for shallow windslab, unstable cornices, and stubborn deep slab.  The windslab and cornice are avoidable and manageable problems in moderate terrain.  Deep slab avalanches are becoming less likely, but high consequences remain if one is triggered.  Below treeline is a solid supportable crust, making the avalanche danger LOW below 2000 feet.

 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

The last couple days have brought steady stiff wind, and combined with light snowfall it has created a subtle stiffer layer of snow on multiple aspects.  Yesterday we took a closer look at a couple small windslabs on the south side of Tincan.  The small, isolated windslabs were becoming less likely to trigger.  There is no persistent weak layer associated, but the subtle structure differences in the layering are just enough to make it break at an interface 1 foot deep.

This kind of windslab is manageable in the right terrain.  It should be expected near ridges, under cornices, and may be easy to trigger the small low volume pockets.  The manageability of this problem is directly related to the terrain.  If you get surprised in steep, high commitment terrain it could very well be dangerous. 

Cornices are building and may be unstable.  One of the small slabs at Tincan was triggered by a naturally failing cornice.  We can expect other cornices around the region to be large and easy to collapse under the weight of a person, snowmachine, or dog. 

Avalanche Problem 2

The deep slab is getting to be less of a problem.  However, the high consequence of a large deep slab avalanche is still affecting my own travel decisions despite the low probability of triggering one at this time.  Causing one today will require the right combination of a steep slope and shallow trigger point. 

Mountain Weather

Temperatures have dropped dramatically over the last 2 days, and despite sunny weather today, it's going to be a cold one.  The highest temperature we see this morning is 10 degrees in Portage and it drops as you get to higher elevations.  Above 3000 feet is negative temperatures. 

Wind has been strong and steady at the ridgetops and in Turnagain Arm recently, a trend which will continue today.  The wind chill factor up high will be quite cold.  We can expect snow plumes blowing off the mountains, building windslabs and creating cornices.  Some areas will see a strong northwest wind through channeled terrain. 

Below treeline the combination of recent thawing temperatures and the deep freeze yesterday has created a solid supportable crust from 0-1500 feet elevation.  There is good skate skiing potential on the crust today around Turnagain Pass.

Wendy will issue the next advisory Sunday morning, January 26th.

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 20, 2019 )

Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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.

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