Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, March 9th 2013 6:32 am by Graham Predeger
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The last couple days brought a refresh of snow to Turnagain Arm and increased the avalanche potential.  Storm snow and high wind caused a spike in the danger yesterday.  Since then the snowpack has had some time to adjust, but we can still expect the upper end of MODERATE danger above treeline where highest storm totals can be found along with a lot of wind loading from 100+mph wind 2 nights ago.  

Given 1-2 feet of new snow in some areas, extra caution should be taken in the mountains today while the snowpack continues to adjust to that new load.

 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.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1

The 2 day storm total has brought more than 2 feet of snow to upper elevations in the Girdwood valley (Alyeska).  Turnagain Pass seems to have gotten about 75% of that amount.  The storm was warmer than we've had recently with rain up to about 500 feet elevation.  Areas below treeline will have denser snow, which dries out the higher you climb. 

We have no reports of unusual avalanche activity from this storm.  All reported avalanches yesterday were of predictable size and character corresponding to the storm event.  Given warmer temperatures and a relatively strong and stable snowpack before the storm hit, our primary concern is the 1-2 feet of storm snow sliding at the new/old snow interface.  This means we aren't very concerned about deeper avalanches.  It also means that we expect bonding to happen relatively quickly. 

We are still within 24 hours of the storm event.  Avalanche 101 protocol tells us that we are still in a higher probability time to trigger avalanches.  Today there is plenty of moderate angle terrain to enjoy the new snow, but big gaming should be delayed another day or two to allow the new snow to settle out and stabilize. 

Avalanche Problem 2

Wind driven storm snow will be deepest on west and northwest aspects today with crossloading on north and south.  Peak wind was 2 nights ago, corresponding with some of the highest intensity snowfall.  Wind diminished yesterday but stayed strong enough to continue blowing snow around.  Any avalanche found today will likely have a wind loaded component to it.  Deeper and stiffer snow should be treated with more suspicion than soft and loose powder. 

Cornices have been a big issue for us over the last several weeks, and given more snow and high wind we can expect larger and less stable cornices again this weekend. 

Mountain Weather

2 day storm totals  

Alyeska top - 28+ inches snow - 2.54 inches of water equivalent

Alyeska mid - 24 inches snow - 1.7 inches water equivalent

Turnagain Pass - 10-12 inches snow est - 0.8 inches water equivalent

Grandview - 0.6 inches water equivalent

Weather today will bring snow showers with 1-3 inches expected.  As this storm system moves through the wind will continue to drop, and temperatures should decrease by a few degrees. 

There is no sun in the forecast this weekend, but clear and colder weather is expected starting Monday.

Wendy will issue the next advisory on Sunday, March 10th.

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: Dec 01, 2018 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed November 21 due to inadequate snow conditions. #hopeforsnow
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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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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