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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Wednesday, January 16th 2013
Created: Jan 16th 6:17 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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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The Bottom Line

With calmer weather, colder temperatures, and less recent evidence of avalanche activity the danger rating drops to MODERATE today for the first time since December 23rd.  A significant amount of uncertainty still exists, and if an avalanche is triggered it may still be very large and dangerous.  Below treeline the danger is LOW.


Primary Concern

The primary concern is still the deep slab problem.  Just two days ago we had a number of very large avalanches, both in Turnagain Arm and Turnagain Pass.  Since that time the rain and snow stopped and the temperature dropped significantly.  Yesterday, just one day removed from the storm, a number of explosive triggers in Turnagain Arm had few significant results. 

The majority of the avalanche activity from the final burst of moisture seemed to be focused on steep, rocky terrain.  This gives us a good starting point on which to base our terrain choices.  The weak layer that may collapse to intiate an avalanche is unlikely to be affected by a skier in areas of deeper snow.  The likely "trigger points" will be shallower, where the stress of a person doesn't have to penetrate through as much strong snow.  Steep north facing lines, complex terrain with chutes and ribs, and generally shallower areas should be avoided today.  This problem should be approached by traveling where the snow is deepest, and testing it where it is thinnest to gauge the worst case scenario.

Yesterday our pit tests on Sunburst found the same weak base layer that has plagued us for most of the season.  The general feel of the layering structure isn't much different from what we've been seeing.  However, the force require to initiate a collapse was significantly greater than it was a week ago.  The bad news is that it still collapses, and it still propagates.  This tells us that triggering a collapse is less likely, but if it happens, a large avalanche is still very possible. 

Pictured below is the before and after of Alpenglow peak which slid on Monday.

 


Secondary Concern

Above treeline there was wind during the last storm system.  Ridges have a stiff, windblown character to them.  Deeper and stiffer snow will be found on the lee side of terrain features.  We don't have a lot of evidence to suggest that windslabs will be unstable, but it is something to watch out for. 


Mountain Weather

The last major storm system left us on early Monday, giving us more than 48 hours since significant precipitation.  Temperatures have dropped since that time, freezing the rain and wet snow that fell below 2000 feet into a surface crust. 

Today, 3-5 inches of snow is in the forecast with light wind.  Temperatures should remain below freezing.  The weather today is not expected to contribute much to the avalanche problem. 

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 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be 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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