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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Saturday, December 27th 2014
Created: Dec 27th 6:24 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.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
Alyeska Resort
The Bottom Line

The avalanche danger is MODERATE in the alpine today.  Dense slabs up to 3’ in depth could be triggered in steep upper elevation terrain.  These slabs sit on a layer of weak snow and have the potential to pull out entire slopes.

In addition recently formed pockets of wind slab up to 1’ deep may be triggered in very steep terrain above 2,500’.

At treeline the avalanche danger is LOW.  Remember that LOW does not mean NO.  In particular pay attention to groups above you when traveling in mid elevation areas with avalanche terrain directly above.  Human triggered avalanches from the higher elevations have the potential to run down into the mid elevations today.


Primary Concern

Clear skies and good visibility will make it easier to travel into the alpine today.  If you find yourself venturing into steep upper elevation terrain you will need to minimize your exposure and treat all slopes above 35 degrees with suspicion.  A layer of buried surface hoar, which we have been tracking, remains intact on many slopes above 2,500’.  Sitting on top of this layer are 2-3’ dense slabs.  

These stiff slabs have the ability to support a lot of weight, especially where they are thickest.  That all changes when you get onto thinner spots of a slab.  It will be possible for multiple tracks to be put down on a slope without avalanching.  It is important to know that tracks do not equate to stability.

This type of slab/weak layer combo is notorious for catching people off guard days and weeks after a storm.  While we have seen signs of the weak layer gaining strength, we also have no snowpack information from any terrain above 3,500’.

If you decide to get onto bigger and steeper terrain today, it will be crucial to manage yourself and your group appropriately:

Avoid trigger points, such as steep rollovers and areas where the snowpack is thin.
Only expose one person at a time, utilize islands of safety, have an escape route, and communicate plans and decisions effectively.  

Keep in mind that it’s a roll of the dice on all terrain over 35 degrees above 2,500'.  Slabs have the potential to propagate across slopes and carry enough volume and speed to injure and bury a person.


Secondary Concern

If venturing into steep upper elevation terrain expect to encounter lingering unstable pockets of wind slab, especially on North aspects.  High winds from 2 days ago formed upside down slabs up to 1 foot in depth.  These slabs may be encountered in starting zones and along cross loaded gullies.  Staying off of snow in steep terrain (over 40 degrees) that has a hollow sound or produces shooting cracks will be the best way in managing this concern today.


Mountain Weather

Yesterday was a mild day for weather around the area.  Winds were calm to light, and predominantly out of the West/Northwest.  Temperatures remained in the 20s F along ridge tops and around 30 F at sea level.  No new precipitation was recorded.

Today expect mainly clear skies with some valley fog as a ridge of high pressure is stationed over the area.  Ridge top winds will be light out of the Nothwest at 10 mph and temperatures at 1,000’ will be close to 30 F.

The next big weather event will involve warm and wet Southerly flow.  Expect above normal temperatures with snow beginning Sunday night changing over to rain by Monday up into the mid elevations.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 28 0 0 30
Summit Lake (1400') 25 0 0 7
Alyeska Mid (1700') 29 0 0 24.1

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 21 WNW 7 29
Seattle Ridge(2400') 24 variable 5 16

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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