Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, January 19th 2013 6:06 am by Kevin Wright
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Some snow this afternoon with moderate wind combined with the lingering deep persistent slab will keep us at MODERATE above treeline.  Fresh wind slabs will start to form today and get bigger by tomorrow.  The deep slab problem is the most dangerous specific issue.  While triggering the deep slab is becoming less likely, the consequences remain high.  Below treeline the danger is LOW.

 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 primary concern today is still the deep slab, which is becoming more stable over time.  We haven't had reports of deep slab avalanches since Monday when the last storm system ended.  The snowpack is showing evidence of strengthening, but a number of tests consistently still show a low probability of initiating a large avalanche. 

This kind of deep slab problem needs to earn our trust.  We have growing confidence, but only to a certain point.  The consequences of causing a full depth avalanche still deserve our respect and some alteration in our terrain choices.  Areas with thinner snow cover are more suspect, and steep rocky terrain may hold the trigger points that could activate a large avalanche.

Now that the deep weak layer has been dormant for a few days we can expect a low possibility of triggering it.  A new significant snow load (which is in the weather forecast for tonight) will increase the chances of deep slab activity as additional stress gets added to the weak foundation (see picture below). 

Avalanche Problem 2

The small amount of snow predicted to fall this afternoon will build wind slabs at higher elevations.  Based on the timing of this storm it looks like this problem will be minor today, but may build into a significant problem tomorrow. 

Mountain Weather

A blizzard watch is in effect for Girdwood, Seward, and Whittier starting this evening.  It appears that this will not have a major effect on the daylight hours today, but it may cause a bump in the avalanche danger by tomorrow.  We can expect increasing wind and up to 5 inches of snow by this evening. 

If you are wondering how the mountains are doing for snow this year check out the graph below.  Our snow depth is slightly above average, and the Snow Water Content measured at 1880 feet at Turnagain Pass (below) is just barely below average. 


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 )

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

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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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