Avalanche Advisory

Turnagain Area Avalanche Advisory
Thursday, February 15th 2018 5:02 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is MODERATE above 1,000' on all aspects. Human triggered avalanches remain possible. Watch for shallow wind slabs on wind loaded slopes and cross-loaded gullies. Additionally, weak layers deeper in the snowpack may still be triggered, creating a larger avalanche. Evaluate snow and terrain carefully.

The danger is LOW below 1,000' where triggering an avalanche is unlikely.


 Show the Complete North American Avalanche Danger Scale
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Special Announcement

Saturday, Feb 17th, from 11am-1230pm - Free Avalanche Beacon Practice with CNFAIC! We will be hosting a short workshop on how to effectively perform a companion rescue. Open to all users and all levels; swing by on your way to the hills if you are just getting into avalanche safety or simply need a refresher! Alaska Mining and Diving Supply will be providing free lunch and the event is also a chance to pay tribute and remember a couple of local shredders lost to the mountains too young, Christoph von Alvensleben and Jeremy Stark. 10 years today #rideinpeace Feb. 15th 2008


Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely


Very Large


Triggering a large persistent slab avalanche up to 2' or more in depth remains possible across the region today. Below the storm snow and recent wind crusts/slabs sits the Jan 21st buried surface hoar that we have been talking about for a few weeks. This layer is roughly 1-2' below the surface. With the recent wind and snowfall adding stress, a person skiing or on a machine may tip the balance and initiate a larger slab avalanche. Triggering a smaller wind slab or a cornice fall may also activate this layer. The snowpack is now at a point where no signs of instability are likely to be present before one of these avalanches is triggered. Assessing the terrain and the potential outcome of an avalanche breaking deeper in the pack is key. Are there terrain traps below you? Cliffs? Are your partners watching and rescue ready? 

Snowpit near the Johnson Pass area that clearly shows the January 21st buried surface hoar. 

 Snowmachine triggered avalanche observed in the Johnson Pass area that likely occurred in the last week. 

Avalanche Problem 2

Wind Slabs

Almost Certain
Very Likely


Very Large


Monday night and Tuesday morning, North and West winds wreaked havoc on much of the terrain around Turnagain, Summit Lake, Portage and the Girdwood Valley. Wind scalloped many snow surfaces, scoured some ridgelines to the rocks and sastrugi was reported on Tincan. Along with the winds, no natural avalanche activity was seen in the Turnagain area, but the Summit Lake region saw several shallow natural wind slab avalanches along with one on Fresno that appeared to step down into an older weak layer. Watch for wind slabs lurking intermixed with the variable surface conditions on the steeper slopes. Pay attention to where the snow feels stiff, looks pillowed, sounds or feels hollow and watch for shooting cracks.  Hard wind slabs tend to break when you are out onto the slope and often fracture above you. Be aware of wind loading patterns in the terrain, especially cross-loaded gullies. 

Wind effect and a wind slab on Maynard Mountain in Portage observed Tuesday. 

Additional Concern

Deep Persistent Slabs

Above 3,000' in the Alpine zones, several old weak layers of facets and buried surface hoar sit near the ground and in the mid-pack. This structure is most pronounced in areas with a thin overall snow cover, such as the South end of Turnagain Pass and the Summit Lake area.  As you plan your day, keep in mind that there are deeper persistent layers that could 'wake up' if you find the wrong spot.

Mountain Weather

Yesterday was partly cloudy with very light evening snow showers in Girdwood. Temperatures were in the 20Fs and winds were easterly 5-15 mph with a few gusts into the 20s and 30s. Overnight temperatures were in the low 20Fs. 

Today will be mostly sunny with temperatures in the low to mid 20Fs. There may be some valley fog. Winds will be northerly 5-15 mph with gusts into the 20s. Temperatures will drop into the teens overnight and skies will become partly cloudy. 

Tomorrow will be partly to mostly cloudy. It is forecast to clear again for Saturday and then cloud up again Sunday. There is uncertainty about what next week will bring with either high pressure or a chance for snow in the forecast!

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 32   64
Summit Lake (1400') 25   0    0    25
Alyeska Mid (1700')  28    trace 0.02   59


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 22   E   23
Seattle Ridge(2400') 24  SE   8     32 

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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