Avalanche Advisory

Turnagain Area Avalanche Advisory
Thursday, December 17th 2015 7:00 am by CNFAIC Staff
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche hazard is CONSIDERABLE above and below treeline today. It will be possible for snowmachiners, riders and skiers to trigger dangerous slabs up to 3 feet in depth on slopes at and above treeline. Below treeline, warm temperatures and the potential for rain on the snowpack will make it possible to trigger slabs 1-2' thick and/or wet loose avalanches in steep terrain.

 Show the Complete North American Avalanche Danger Scale
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
Special Announcement

Fireside Chat #3 – Human factors and decision-making, TONIGHT, Dec 17th!! Join our newest CNFAIC forecaster, Aleph Johnston-Bloom, tonight from 6:30-8:00pm in Girdwood at the Glacier Ranger Station (Forest Service office) for an introduction to what avalanche professionals and psychologists refer to as the “human factor” as it relates to decision-making in the backcountry.

CNFAIC is hosting a Free Avalanche Rescue Workshop on Sunday, December 20th at Turnagain Pass. This is a great opportunity to practice beacon searches, learn strategic shoveling techniques and meet local forecasters! This workshop is open to everyone and anyone, novices and experts.

Avalanche Problem 1

There are a variety of potentially dangerous storm related issues today. Caution is advised travelling in avalanche terrain, these conditions warrant careful route finding and conservative decision-making. We received a 6-8" of snow that started falling in late the afternoon yesterday. We have now received over 3" of water equivalent in the past week, equating to over 3' of new snow in the Alpine. With the snow available to transport, winds over the past two days have created slab conditions on leeward slopes. An observer reported cracking in the upper 18" on Seattle Ridge yesterday and triggering a small pocket of wind slab. This set-up may be more developed today and easier to trigger. 

In addition, temperatures are rising and may result in an "upside-down" structure and instabilities within the new snow. This may be more pronounced in the lower elevation bands. This means there is the potential for both wind slabs from the wind loading and soft storm slabs from the warming trend of the storm.

The snow line may rise over 1000' today resulting in rain on snow in the lower elevation terrain. This could add additional load and saturate the snow on the ground. Wet-loose avalanches may be possible.

Watch for Red Flags (signs of instability): cracking, whumpfing and recent avalanching are all signs that the snowpack is stressed. New snow and wind may be actively creating dangerous avalanche conditions today.

Additional Concern

We have been continuing to monitor the layer of Near Surface Facets and Buried Surface Hoar since they were buried at the beginning of this stormy period. So far they have been unreactive. However, as the slab and the load on top of this layer continues to grow they are worth remembering. This is an added reason for caution today in avalanche terrain.

Mountain Weather

Yesterday was overcast, snow started in the afternoon and continued overnight, depositing 4-8" of snow. Northeasterly winds blew in the 20's and gusted into the 40's. Temperatures were in the 20Fs. 

Today snow is forecasted to continue in the morning transitioning to scattered snow and rain showers after noon. Temperatures will be in the high 20Fs to upper 30Fs. Winds will be Northeasterly 15-25 mph. New snow accumulation of 2 to 4 inches is possible today. Snow showers will continue overnight into tomorrow.

The low in the Gulf in conjunction with the occluded front will continue the pattern of unsettled weather in the area for the next few days with next stronger pulse of moisture forecasted for the weekend. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 26  .7  42 
Summit Lake (1400')  20  2  .2 15 
Alyeska Mid (1700') 27   4 .3  35 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  19 ENE   23  49
Seattle Ridge(2400')  21  n/a n/a  n/a 

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, 2019 )

Glacier District
Johnson Pass: ClosedClosed as of 4.3.19
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: ClosedClosed as of 5/6. Thanks for a great season all, see you next winter!
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Closed
Lost Lake Trail: ClosedClosed as of 3.22.19 due to lack of snow
Primrose Trail: ClosedClosed as of 4.3.19 due to lack of snow
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: ClosedClose as of 5.1.2019
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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.

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