Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, December 25th 2016 7:00 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

A BACKCOUNTRY AVALANCHE WARNING has been issued through the National Weather Service for the Turnagain Pass area and surrounding mountains. 

Heavy snowfall and strong winds have created a HIGH avalanche danger in the mountains surrounding Turnagain Pass, Girdwood Valley, Portage Valley and areas on the Kenai seeing heavy snowfall. Dangerous avalanche conditions are expected on all slopes 30 degrees and steeper - including runout zones. Avalanches are expected to release naturally, be easily triggered by people and could run to elevations below 1,000'. 

Travel in avalanche terrain is NOT recommended. Today is a day to hunker down, unwrap presents, hit the slopes at Alyeska or your local ski hill/trails or get your snowmachine ready for a possible motorized opening soon!  

 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

***Carter Lake and Snug Harbor areas are open to motorized use. Please respect other closures across the Forest. The Forest Service is monitoring this storm and will open more areas as soon as there is enough snow to prevent resource damage to underlying vegetation. The Forest thanks you for your patience!

Avalanche Problem 1

All I want for Christmas is a big snow storm
A big snow storm
Just, a big snow storm...

Merry Christmas riders and skiers!!! It seems as though Santa has answered our wishes and brought us a long awaited 'Chugach Storm'! Yes, it's raining at sea level, but above 500' there is sticky new snow blanketing the mountains. Unfortunately, this is too much to play with today as by this afternoon we could be up to 20+" of new snow in 24 hours. 

STORM TOTALS in the upper elevations so far:

Turnagain Pass:     12" and counting
Girdwood Valley:    12" and counting
Summit Lake:          2-4"  

EXPECTED AVALANCHE ACTIVITY:  This is a text-book "rapid loading event". Not only is 2' of snow in 24 hours an avalanche maker in itself, this snow is falling on a VERY weak surface. The loose faceted snow combined with surface hoar (that we've been skiing/riding on the past several days) will act like ball bearings and inhibit the new snow from sticking to the mountainsides. Hence, widespread natural slab avalanches up to 2' thick are likely and human triggered avalanches very likely. Winds should stay strong along with the snowfall through tonight and wind loaded slopes could harbor slabs as thick as 4'. 

Treed areas such as the Tincan Trees:  Storm snow slab avalanches 1-2' thick are likely to be triggered in the trees. The new snow is denser than the underlying old snow - creating an upside down and unstable snowpack. Avoiding slopes over 30 degrees in treed areas is also recommended.

Check out the Turnagain Pass Snowstake loop at the RWIS DOT station. Thanks to the DOT for getting this station up and running for the winter!


Mountain Weather

During the past 24-hours we have seen the start to our 'Christmas Storm'. Snow began falling at noon yesterday and totals up to 6am this morning are above and in the table below. Winds ramped up dramatically yesterday morning from the East and have remained in the 30's mph with gusts over 60mph on the ridgetops. We have limited wind data with the Sunburst weather station down, but it's no question the winds are very strong with this system. Temperatures have warmed from the teens to the mid-20'sF above the trees and into the low 30'sF at 1,000'. The rain/snow line looks to be hovering near 500'. 

We are expecting another 10-12" of snowfall today with around 1" of water equivalent. Winds are expected to remain strong from the East in the 30's mph with gusts to 75mph on the ridgetops. Temperatures look to stay warm with a rain/snow line remaining around 500'.

Tonight and tomorrow the system slowly moves out and we should see instability showers adding another few inches along with cooler temperatures. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 27  12  0.8  36 
Summit Lake (1400') 30  0.2 
Alyeska Mid (1700') 28  0.7  24 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') Under repair   Under repair   Under repair   Under repair  
Seattle Ridge(2400') 22  SE  29 60 

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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