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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Wednesday, February 13th 2013
Created: Feb 13th 6:50 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

Continued snowfall in small to moderate amounts, combined with a mid elevation crust keeps us at MODERATE above treeline.  The avalanche problem ranges from small wind slabs, to larger and more dangerous but less likely persistent slabs.  The crust problem seems to be at a specific elevation band, but limited information is keeping us from being confident about where to avoid that problem. 


Primary Concern

On Monday we got a report of a disconcertingly large skier triggered avalanche in the Girdwood valley.  It appears to have been remotely triggered near the 2700 foot elevation and slid on or under a 2 week old crust which is now buried 2-3 feet deep.  Yesterday we confirmed the reactive nature of that weak layer.  See the full test results on our observations page.  Our testing found a specific elevation band between 2000 and 3000 feet contains a series of crusts and facets that can collapse under the weight of a person and propagates large distances.  Snow pit testing shows only moderate strength, and failure happens in a clean and fast nature. 

We don't know how widespread this problem is.  It appears to be common in the Girdwood valley, but so far we have few reports across Turnagain Pass that correlate to a reactive ice crust.  However, it should be assumed to be common at the mid-elevation band regionwide until we prove otherwise.  This problem is not likely to go away quickly, and may get worse before it gets better. 


Secondary Concern

Wind slabs, large cornices, and building storm snow will be a problem above treeline.  Over the last week, no single day has brought a large amount of snow, but the combined 7 days equals close to 20 inches of new snow at Turnagain Pass and perhaps double that amount in Girdwood.  Wind has been consistently strong.  We can expect to find areas of stiffer and deeper wind deposited snow which may be triggerable by a person.  Any steep wind loaded terrain above treeline should be approached with caution corresponding to the terrain consequences. 


Mountain Weather

Over the last week, each day has brought 1-4 inches of snow to Turnagain Pass.  The last 24 hours was similar with about 3 inches new snow.  Temperatures have been in the mid 20s with a moderate east wind reaching into the 30s and 40s yesterday.

Today looks like more of the same.  An inch of snow is expected this morning, with snowfall tapering off by noon.  Tonight 4-8 inches is expected and increasing wind 40-60mph as the next frontal system moves across southcentral Alaska. 


Wendy will issue the next advisory tomorrow morning, February 14.

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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