Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, December 10th 2017 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

The avalanche danger remains CONSIDERABLE on all aspects and elevations above 1500' today and is expected to increase to HIGH tonight. Another pulse of snow, rain and wind is headed our way and will continue to load a fragile and weak snowpack. Natural avalanches are possible and human triggered slab avalanches 2-4+ feet deep are likely on slopes steeper than 30 degrees. Remote triggered avalanches from below slopes, next to them and above them are possible. Cautious route-finding and conservative decision-making are essential. 

Below 1000’, where little snow exists, the avalanche danger is MODERATE where an avalanche releasing from above could send debris through steep channeled terrain into this zone. 

**Summit Lake weekly Summary can be found HERE.

 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Special Announcement

Elevated avalanche danger exists throughout Southcentral, AK due to continued stormy weather. If you are headed to Valdez or Hatcher Pass check out the Hatcher Pass Avalanche Center observations and forecast at Valdez Avalanche Center avalanche advisory at  Also there was a report Friday, Dec 8th of a close call with a large snowmachine triggered avalanche near Petersville, an area without much avalanche information. 

A reminder that motorized use on Turnagain Pass remains closed due to insufficient snow cover.  Please see riding area status at the bottom of this page for the most up-to-date information.

Avalanche Problem 1

As has been the theme for December, another warm storm is on the doorstep. This one will be arriving today. Winds have already picked up from the East and after a pulse of heavy precipitation for a few hours overnight, light precipitation is expected today before ramping back up tonight. I hate to say it, but the warmest temperatures we have seen so far have occurred during the past 24 hours. This has bumped the rain/snow line up to 2,600' and possibly created some wet avalanche activity - more on that below.

Avalanche conditions: Dangerous. The weak faceted snow that sits underneath the past 2 weeks of storm snow continues to prove itself reactive. Although this layer is slowly becoming more and more buried (20"-4+' below the surface) and showing signs of being slightly more stubborn to trigger - it remains our primary concern. Future avalanches triggered, either by the upcoming storm(s) or a person, are becoming larger and could allow a person/people on to them before releasing. Keep in mind slopes that have already avalanched could reload and release again. 

This storm's new snow and wind at the high elevations will be creating another set of avalanches problems including wind slabs, storm slabs and cornice falls. All these storm snow issues will likely be hard to see in the clouds today, however, even small avalanches due to the storm have the potential to trigger a larger slab breaking in the weak facets near the ground. 

If you are headed out to the mountains today, we recommend staying off slopes steeper than 30 degrees with nothing steeper above you, be careful to avoid runout zones and bring your rain coat.

If you look closely, you can see a streak of debris down Todd's Run on the North side of Tincan. This avalanche occurred sometime on Thursday, Dec 7th. 


Natural slab avalanche occured sometime between Friday night and Saturday (Dec 8-9) in steep terrain on Seattle Ridge - photo Joe Kurtak.

Pictured below is Seattle Ridge and the common motorized up-track as seen from Tincan. This slope, along with many other in the Turnagain area, has not avalanched and suspect to do so. Remeber, weak layers are guilty until proven innocent.


Avalanche Problem 2

Rain falling up to, and possibly higher, than 2,600' will be falling on snow. This is a text book case for creating wet avalanches in the elevation band of 1,000' - 2,600' and possibly higher. Little to no snow sits below 1,000' and therefore the hazard there is due to avalanches releasing above sending debris into this zone. Not only wet loose slides are expected, but wet slab avalanches could occur today and through tomorrow with these very warm temperatures.

Mountain Weather

Yesterday, overcast skies and light precipitation were over the region. A pulse of heavy rain (~ 0.5") occurred below 2,500' overnight with an estimated 5-7" at the higher elevations. A 24-hour total of precipitation was 1" of rain in the Girdwood Valley and slightly less at Turnagain Pass with roughly 6 - 12" of snow in the Alpine above 2,500'. Temperatures as you can expect with this high rain line, were warm - climbing up to 33F at 3,800'...! Winds were light yesterday and have increased overnight with averages in the 20-30's mph with gusts up to the 60's from a generally Easterly direction.

Today, another shot of rain, snow and wind is arriving. Winds have climbed as mentioned overnight and are expected to remain strong today through tomorrow. Ridgetops should see averages in the 20-30's mph from the East with gusts up to 70mph or more. Precip amounts will be moderate through the day and significant tonight with a rain/snow line around 2,600-2,800'. Around .5" rain expected today (5-7" snow in Alpine) and 1" tonight (10-12" snow in Alpine). 

*There is 'High Wind Watch' issued by the NWS tonight through tomorrow morning for Portage Valley and Turnagain Arm. 

The longer term forecast continues with an active pattern, yet cooler temperatures should arrive Monday for a brief period, before a more significant cooiling trend is expected Wednesday through Friday. This means a lowering of the rain/snow line, cross you fingers!


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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 37  0 (rain)  0.7  23 
Summit Lake (1400') 36  0 (rain)  0.2  10 
Alyeska Mid (1700')  36   0 (rain)  1.07  18 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 30  ENE  21  64 
Seattle Ridge(2400') 33  SE  19  59 

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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