Avalanche Advisory

Turnagain Area Avalanche Advisory
Wednesday, December 13th 2017 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger remains HIGH due to heavy rain, wet snowfall and strong winds. A very potent warm and wet storm cycle has saturated the snowpack below 3000' where triggering a wet slab avalanche will be likely today. In the Alpine triggering a storm snow avalanche 2-4 feet thick is also very likely. Travel in avalanche terrain is NOT recommended

Below 1,000’, where little snow exists, there is a CONSIDERABLE avalanche danger for debris running into steep or channeled terrain.

**Summit Lake area also has elevated avalanche danger and the weekly summary can be found HERE.

 Show the Complete North American Avalanche Danger Scale
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Treeline / 1,000'-2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
Special Announcement

Elevated avalanche danger remains throughout Southcentral, AK due to continued stormy weather. If you are headed to Hatcher Pass check out and for Valdez, valdezavalanchecenter.orgAlso, there have been reports of unstable snow and human/natural triggered avalanches near Petersville and the Dutch Hills area.

Scholarship Applications due on Dec 15th. The Friends of the CNFAIC have two scholarships dedicated to avalanche education for skiers, snowmachiners and all user groups. The funds generated to make these possible are in celebration of Rob Hammel and Amy Downing, their love and passion for the mountains, and to help others stay safe. 

Avalanche Problem 1

Wet Slab

Almost Certain
Very Likely


Very Large


Above freezing temperatures, strong winds and periods of heavy rain have impacted our forecast zone over the last four days causing a widespread avalanche cycle in the mid elevation band. In the last 24 hours Turnagain Pass received 0.9” of rain and Girdwood received 1.56” of rain, with the heaviest precip happening between 1am and 6am this morning. On Monday dozens of wet slab avalanches were observed throughout Turnagain Pass on all aspects below 3000’. Rain/snow line has been hovering between 2000’ and 3000’ and snow totals along the road are quickly shrinking. 

 Dec.10 - Dec.13 Storm Totals (Rain to 2500')

  • Turnagain Pass (Center Ridge Snotel) = 4.0” of Rain
  • Girdwood (Alyeska midway station) = 6.0” of Rain

The avalanches seen on Monday released near the ground on old weak faceted snow. The most interesting (and scary) avalanches occurred on the West facing terrain of Tincan below 2500’, an area many folks go when the avalanche danger is elevated. This speaks to the powerful nature of a saturated snowpack and indicates that even small terrain features are suspect. The snowpack below 2500’ is isothermal, and triggering a small slope from below or getting caught in a terrain trap would be unsurvivable. Until the snowpack has a chance to drain and form a crust the avalanche danger remains high and travel in avalanche terrain is not recommended. 

Photo taken on Tuesday, Dec.11 during a period of good visiblity. Recent avalanche on West facing terrain of Tincan at 2500'. Several more avalanches also occured in the lower elevations on small terrain features and on Todd's run. Check out the observation HERE.  


Photo taken on Tuesday, Dec.11 during a period of good visiblity. Recent avalanche activity on SW aspect of Eddies. Several more avalanches occured lookers left on more West facing slopes. Check out the observation HERE. 



Avalanche Problem 2

Storm Slabs

Almost Certain
Very Likely


Very Large


Wet and heavy snow has been falling in the Alpine, which becomes drier with elevation. Based on total rain at the mid-elevations stations an estimated 4-5 feet of snow has accumulated in the alpine this week. New snow and strong Easterly winds have been loading a weak pre-existing snowpack and as of this morning very little information is known about avalanche activity in the upper elevations. Storm snow avalanches that include storm slabs, wind slabs and cornice breaks all can be expected today. There is also potential for a larger more dangerous avalanche to release on a weak foundation near the ground. This size avalanche could run into the lower elevations in steep or channelled terrain. Evidence of such avalanches have occurred in big terrain along the Seward Highway like Pyramid’s West face and other indicator paths. As of Tuesday, the last time we could see into the Alpine, many of the upper elevation zones of Turnagain Pass remained intact. Again, the message is simple for today, avoid avalanche terrain until the snowpack has time to adjust to its new load.

Most of the snow has melted below 1000' with the exception of some larger avalanche paths where debris can been seen, like the West face of Pyramid, lookers right side of speed limit sign.  

Mountain Weather

Yesterday another  0.9” of rain fell in Turnagain Pass and 1.56” of rain fell in Girdwood. Temperatures remained above freezing, averaging 35F at 1000’. Easterly ridgetop winds averaged in the 20’s with gusts in the 60’s (mph). Temps warmed in the evening and Seattle Ridge weather station was reporting 31.5F at 2400’, estimating rain/snow line to be around 2000’. The most intense precipitation occurred this morning with half the total precip amounts falling between 1am to 6am. 

This morning as a strong front passes over Southcentral and weakens heavy rain will transition to showers with another .5” of rain expected throughout the day. Temps are expected to cool slightly be this evening bringing rain/snow line 1500’. Easterly ridge top winds will start to decrease in the morning to 10-20mph. Scattered rain showers are possible overnight.  

A strong South to North storm pattern that has impacted our region with warm temps and numerous storms is expected to transition to more of Southwesterly flow in the comming days. There is talk of temperatures starting to fall back towards freezing level with another series of storms on tap for the weekend starting Friday, hopefully in the form of snow instead of rain.  At this point there is uncertainty on timing and intensity and what form of precip will be falling from the sky. 

** Sunburst weather station is not working as of 12/11/17 due loss of battery power.

Snow along the highway is quickly shrinking. Tincan trailhead creek has open water and the Southern end of Seattle Ridge dirt and veggitation are visibile. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35  0.9  24 
Summit Lake (1400') 37  0.3   9
Alyeska Mid (1700') 34   1.56 17 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') *n/a  *n/a   *n/a   *n/a  
Seattle Ridge(2400') 29  SE  23  65 

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.

If you have comments or questions regarding CNFAIC operations or winter recreation management, please email
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