Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, December 9th 2017 6:09 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 is CONSIDERABLE on all aspects and elevations above 1500'. Recent storms have loaded a weak snowpack. Triggering a slab 2-4+ feet could release on slopes steeper than 30 degrees and remote triggered avalanches are possible. Cautious route-finding, conservative decision-making are essential today.  

Below 1000’, where little snow exists, the avalanche danger is MODERATE where an avalanche could run into steep channeled terrain. 

**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 recent storms this week. If you are headed to Valdez or Hatcher Pass check out the Valdez Avalanche Center avalanche advisory at and Hatcher Pass Avalanche Center observations and forecast at  Also there was a report yesterday of a close call near Petersville, an area  area without much avalanche information. Luckily all are ok.

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.

TODAY in Seward: Know Before You Go - Avalanche Awareness at the Seward Community Library, December 9th, 1 pm - 4 pm | FREE Join CNFAIC for a great intro to avalanche recognition and rescue, including hands-on beacon practice.

Avalanche Problem 1

Yesterday’s benign weather and patches of clear skies allowed for a good look around Turnagain Pass to inventory the results of Thursday’s storm. Evidence of some natural avalanche activity could be seen in steep channeled terrain, but many slopes still remain intact. Incremental loading from multiple storms over the last two weeks has buried a reactive layer of weak faceted snow near the ground. Facets have been found above and below a melt/freeze crust near the ground that is acting as a slick bed surface. This poor structure appears to be widespread both in the middle and upper elevations throughout Turnagain Pass and Girdwood. Last week when the slab was thinner observers reported “whumpfing” sounds on a daily basis including a very loud collapse that remote triggered two avalanches on Tincan, one on each side CFR ridge. Today triggering a large propagating avalanche is likely in avalanche terrain, especially in places where the snow pack is thinner and easier to penetrate the weak layer.  Keep in mind that the Northern end of Turnagain Pass has seen heavier precipitation and higher snow totals in the alpine compared to the Southern end of Turnagain Pass. This means that triggering an avalanche may be easier in places like Sunburst, Magnum or Cornbiscuit that have less snow. Triggering an avalanche could propagate an entire slope releasing to the ground and running the entire slide path. The big take home message is dangerous avalanche conditions exist and there is limited info beyond Tincan. Remember this is not an avalanche problem that can be out smarted or easily managed. Avoiding all runout zones and avalanche terrain steeper than 30 degrees is essential today.  


A test pit at 3100' yesterday revealed weak faceted snow below and above melt/freeze crusts formed in October. 


Debris at the bottom of steep channeled terrain on the North side of Tincan. New debris was also seen in Todd's run that wasn't there before the Thursday storm. 


An avalanche seen yesterday that likely released mid to late storm on Cornbiscuit Thursday. Cornbiscuit is a good example of where the snow pack is thinner and could be easier to trigger a persistent slab. 


Avalanche Problem 2

Strong Easterly winds this week have loaded leeward aspects, cross loaded many gullies and loaded corniced ridges. Human triggered wind slab avalanches or cornice falls are likely, but what is more of a concern is the potential for one of these to trigger a much larger and dangerous persistent slab avalanche as discussed above.  AGAIN today is not the day to be pushing into avalanche terrain! 

Additional Concern

Yesterday clear skies allowed for a superficial surface crust to form to 2500’. Today as temperatures rise above freezing at ridgetops and clouds move overhead, expect this crust to start breaking down. Wet loose avalanches could occur later in the afternoon with the arrival of rain showers. Pay attention to snow conditions becoming wet and avoid terrain traps or steep terrain features. Don’t forget above freezing temperatures is a red flag warning to avoid avalanche terrain.

Mountain Weather

Yesterday skis were broken with patches of blue sky in the afternoon and evening in Turnagain Pass. Temperatures remained above freezing at 1000’ and averaged 28F near ridgetops. Overnight temperatures have been on a steady incline and have reached 30F at Sunburst Wx Station (3800’) and 34F at Seattle Ridge Wx Station (2400’). No new precipitation was recorded in Turnagain Pass. Winds were light from the East 5-15mph yesterday and have increased to 15-30mph from East this morning. 

Today temperatures are expected to remain above freezing even in the upper elevations. Scattered rain showers are possible today with 0.16” of rain that could reach 3000’. Easterly ridge top winds 10-30mph are expected to increase into the 40s this evening. Unusually warm air will remain in the upper elevations and precipitation is expected to increase early this evening with a potential for 0.5” of rain tonight.   

Warm, wet and windy weather pattern is expected throughout the week as a series of low pressure systems continue to impact our region. Sunday evening through Monday, another strong storm is on tap and should bring strong winds, above freezing temps and a mix of rain and snow in the upper elevations. 

*Center Ridge SNOTEL is reporting erroneous temperature data. See Turnagain Pass DOT weather station for accurate temperature at 1000'.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') *36  26 
Summit Lake (1400') 30  10 
Alyeska Mid (1700') 34  trace  0.05  19 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 28  ENE  30 
Seattle Ridge(2400') 31  SE  13  27 

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: Mar 15, 2018 )

Glacier District
Johnson Pass: Open
Placer River: OpenPlease avoid private property and AKRR job site at Luebner Lake. Cross railroad tracks if needed, do not ride down tracks, it is illegal.
Skookum Drainage: OpenCross railroad tracks if needed, do not ride down tracks, it is illegal. FYI, Skookum drainage closes to Snowmachines on 4/1 as per the Chugach NF plan.
Turnagain Pass: Open
Twentymile: OpenCross railroad tracks at designated spot as you leave the parking area.
Seward District
Carter Lake: Open
Lost Lake Trail: Open
Primrose Trail: Open
Resurrection Pass Trail: OpenResurrection Pass trail is open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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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