Avalanche Advisory

Turnagain Area Avalanche Advisory
Thursday, December 11th 2014 7:00 am by John Fitzgerald
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is mainly LOW in the alpine, with isolated pockets of MODERATE danger.  In steep starting zones above 3,000’, the possibility exists for triggering old wind slabs up to 18” in depth.  These slabs will be difficult to trigger but hold some potential to propagate across slopes.  Giving the snowpack another day to adjust to the most recent load by sticking to slopes 35 degrees or less will be your best bet.

At treeline, in the mid elevations (1,500'-2,500'), a rain crust caps the surface and has locked the snow into place.  The avalanche danger is LOW in this elevation band today.

Below treeline (1,500 and lower) there is not enough snow cover for avalanches to be of concern.

Early season hazards such as rocks, stumps and open water pose the greatest potential for harm.  A slick and impermeable rain crust between 1,500-2,500’ in elevation will also require careful travel.

 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.
0 NO RATING Below Treeline / Below 1,000'
Special Announcement

Installment 2 of our Fireside Chat Series takes place tonight at 6:30pm at the Alaska Avalanche School in Anchorage.  CNFAIC Forecaster Wendy Wagner will talk about Avalanche Basics and Rescue Fundamentals.  This event is FREE and open to anyone interested.  Check the Calendar tab for more detailed info on this and other upcoming events.

Avalanche Problem 1

Yesterday my partner and I found generally stable snow in the higher elevations.  We found evidence of extensive avalanche activity that had occurred during and immediately after the most recent storm on Tuesday Dec 9th.  Looking under the snow surface showed us mostly strong snow with one exception.  We were able to see some propagation potential along a weak layer 18" below the surface.  Because of this result and only minimal information since the storm, it will be wise to treat steep upper elevation slopes with a healthy dose of respect.  While the weak layer in question in our snowpit is one that typically stabilizes quickly, I’m not ready to jump into this type of terrain without gathering more information from below the surface.  The general trend today will continue to be towards better stability.  The likelihood of triggering an avalanche is on the low end of the scale, BUT there are stiff older wind slabs that are sitting on weaker snow.  These older wind slabs will be difficult to recognize, as they are blanketed by low density powder.

Venturing into steeper terrain in the upper elevations will require advanced snowpack assessment skills and the ability to detect old wind slabs hiding underneath 8-10" of light powder.  You can also hedge your bets by sticking to terrain 35 degrees or less in the alpine today.

As mentioned above, early season hazards and a stout & slick rain crust in the mid elevations are legitimate concerns and require careful travel in order to avoid injury.

Additional Concern

Yesterday we observed one glide avalanche on the East face of Pyramid that had moved 10-20 feet downhill over the past day.  While glide avalanches are not a widespread issue currently, it is worth keeping them in mind.  Both Eddies and Tincan have numerous older glide cracks that have not moved over the past couple of weeks.  The nature of glide avalanches makes it very difficult to know when they might release.  With this in mind, it is best to steer clear of glide cracks and to keep track of where they are.

Mountain Weather

Earlier this week rain, snow, warm temps and moderate winds created unstable conditions throughout the area.  Since Tuesday Dec 9th, the weather has quieted down and allowed the snowpack to adjust.  

Temperatures over the last 24 hours have cooled into the low 20s F.  Ridgetop winds have been light and there has been no new precipitation.

Today expect a continuation of this quiet weather.  Skies will be mostly clear with some fog in the valleys.  Temperatures will be in the low 30s F at 1,000’ and in the mid 20s F at ridgetop levels.  Winds will be light out of the North at 5-15 mph.  No new precipitation will fall today.

The extended outlook is showing a chance for snow and possibly rain at the lower elevations as we head into the weekend.

PRECIPITATION 24-hour data (6am - 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 29  0  0 18
Summit Lake (1400') 22  0  0  4
Alyeska Mid (1700') 29  0  0  11.8


RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  25  WNW  6  18
Seattle Ridge(2400')  28  var  8  23

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: Oct 05, 2019 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed. Will be open for the 2019/20 season pending adequate snow cover.
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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