Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, January 8th 2018 5:17 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 is MODERATE on all slopes above 2,000' in elevation. Slab avalanches breaking 1-3' thick in weak layers under the New Year's snow will be possible to trigger. Slabs may release after several tracks are on the slope and remotely triggering an avalanche from below or adjacent to a slope is possible. Additionally, triggering a larger slab breaking near the ground remains possible at elevations above 3,000'. The danger is LOW near 2,000' and below.

 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.
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Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely


Very Large


It has been four days since any known avalanche activity has been seen. The New Year's storm snow has now settled to around 12 - 20" at Turnagain Pass and to 20-30" in the Girdwood Valley. The buried surface hoar that is the culprit for last week's avalanche activity sits right under the New Year's snow. This layer is slowly gaining strength and the slab is becoming more stubborn to trigger. However, we are not out of the woods. Snow pit results are still showing this layer to be reactive and to propagate - meaning human triggered slabs are possible if one hits the right spot on the slope. Additionally, there are slopes that avalanched in early December which have a thinner snowpack and harbor another set of facets under the pack. Essentially, we have a thin snowpack with various weak layers.

These problems are relegated to above ~2,000'; due to rain falling up to 2,000-2,300' on Jan 2nd, which has turned the slab into crusts at these elevations and below. (Remember from your level 1 avalanche course, to have a slab avalanche you must have a slab, not just a weak layer.) Hence, many folks were out enjoying terrain around 2,000' yesterday without incident, yet most terrain above this, and in the 3,000'+ range, remains untested. Here is a video from 3,000' yesterday: 


*For those riders and skiers headed out for today's sun, keep in mind that travel in the upper elevations is where triggering a slab is most likely. This is above 2,500' where NO crusts exists in the top foot of the snowpack and the snow quality is best. Remotely triggering a slab is possible, several tracks may be on the slope before a slab releases and no signs saying 'the slope is unstable' are likely to be present. Larger slopes are more suspect as well and those with rocky features. Safe travel habits are always key, but especially when dealing with persistent and deep persistent slab avalanche problems: exposing one person at a time, having an escape route planned and watching your buddies closely.

The SLAB and WEAK LAYER we are talking about - the "thin grey line"...


In the photo below, the SLAB fails and cracks but doesn't quite want to fall into the pit on this low angle slope when a snowmachiner side hills just over the pit wall.

Many folks out enjoying terrain in the near 2,000' elevation zone and below where triggering an avalanche is unlikely. (Photo from Main Bowl/1st Bowl in Seattle Creek drainage)


Old avalanche debris from Jan 2nd - this is at 2,000' and these lower slopes that were rained on when the avalanche occurred are now frozen and stable. (photo Ray Koleser)


Avalanche Problem 2

Deep Persistent Slabs

Almost Certain
Very Likely


Very Large


At high elevations above 3,000’, human triggered large and dangerous deep slab avalanches are still possible. Weak sugary snow (basal facets) near the ground is creating a low probability/high consequence avalanche problem that is impossible to outsmart and will take a long time to heal. A big trigger like a snowmachine or a slab avalanche in the upper layers of the snowpack may be enough force to initiate a deep slab avalanche. Likely trigger spots will be in thinner areas of the snowpack that are connected to large, loaded slopes. Cautious route-finding is essential. This includes thinking about the remote trigger potential from below.

Additional Concern


Mountain Weather

Broken skies and valley fog were over the region yesterday. Winds were light and variable and temperatures were in the mid 20'sF. Overnight, valley bottom temperatures have dropped to the teens as an inversion has developed. 

Today, we can expect mostly sunny skies and light and variable winds. Temperatures should climb to the mid 20'sF at 1,000' by the afternoon and remain in the mid 20'sF along ridgelines. 

Snow flurries are on tap for tomorrow with little accumulation expected and temperatures should remain cool enough for any flurries to fall to sea level. This weekend looks to be a chance for another shot of snow - stay tuned!

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 27  42 
Summit Lake (1400') 16 14 
Alyeska Mid (1700') 25   37


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24  NE 
Seattle Ridge(2400') 25  NE 

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.

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