Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, January 13th 2018 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

An avalanche warning has been issued for Turnagain Pass, and the avalanche danger remains HIGH at all elevations due to rain, heavy snow, strong winds and above freezing temperatures.  Natural and human triggered wet slab avalanches and storm slabs 2-4 feet deep will be likely today in avalanche terrain and could run to valley bottoms. Travel is not recommended on or near slopes steeper than 30 degrees including runout zones. 

*Portage and Whittier, outside of our advisory zone, has received double the amount of precipitation as Turnagain Pass and another 2” of rain is expected today. Avalanche activity in these zones may run to valley bottoms.  

For information about the Summit Lake avalanche conditions click HERE.

 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.
4 High Below Treeline / Below 1,000' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Special Announcement

An avalanche warning has been issued for the Turnagain Pass advisory zone including Girdwood Valley and will be in affect through Sunday, January 14. 

 **How about an alternative activity? There is a FREE avalanche rescue clinic at Hatcher Pass today where you can practice your rescue skills with the guidance of professional instructors - clinic runs from 11am - 1:30pm at the Gold Mint parking lot. 

Our advisory page has changed! Information on the changes can be found HERE

Avalanche Problem 1

Wet Slab

Almost Certain
Very Likely


Very Large


Rain on snow is expected below 1500’ and will be adding significant stress to the snowpack in the mid and lower elevation zones. A weak interface (facets and buried surface hoar sitting on a crust) is underneath yesterday’s 20” of storm snow. Add today’s rain and this is a perfect recipe for wet slabs. Natural and human triggered wet slabs 2-3 feet deep are likely on slopes steeper than 30 degrees including both large and small terrain features. Triggering this kind of avalanche will be impossible to escape and could be unsurvivable. It will be very important to avoid terrain traps and being near the runout of larger slopes. 


Remote triggered avalanche on Tincan yesterday. This is a good example of a small terrain feature that could be releasing naturally if rain saturates the snowpack today. Photo credit: Matti Silta


Avalanche Problem 2

Storm Slabs

Almost Certain
Very Likely


Very Large


Yesterday 20” of new snow was observed in Turnagain Pass and today another 12-20” of heavy snow is expected in the upper elevations above 1500’. Natural slabs 3-4 feet deep will be likely today and human triggered avalanche very likely. Strong Easterly winds in the 40’s with gusts in 90’s are also anticipated. All 6 Red Flag warning signs were observed yesterday at Turnagain Pass. This includes a remote triggered avalanche on Tincan,  large shooting cracks, collapsing “whumpfing sounds”, rapid loading due to heavy snow and strong winds, and warming temperatures. All of this new snow has fallen on surface hoar and near-surface facets and slabs will be easy to trigger. Below 2000’ these weak layers are sitting on a slick crust  and a slab could easily catch you by surprise, even in the protected trees of Tincan or getting your snowmachine stuck under a small steep terrain feature. Strong winds today could trigger a large natural avalanche that could run down to valley bottoms. Maintaining a safe distance from the runout zones of all larger slide paths including Repeat Offender will be important. Remote triggering an avalanche from below or above is also possible. Basically today is a good day to avoid the mountains around Turnagain Pass. In fact this is a good day to head to Hatcher Pass and practice your avalanche rescue skills. Click HERE for details about the free clinic. 

A very large shooting crack on a wind loaded terrain feature was intentially triggered by a snowmachine near the motorized lot yesterday. Windloading has created variable slab depths. Slabs could be as deep as 4-5' on leeward features. 


Additional Concern

Persistent Slabs

Natural and human triggered avalanches today could step down to deeper layers of the snowpack producing a very large avalanche depending on the size of the slope. A layer of buried surface hoar from the New Year’s holiday has been showing propagation potential in test pits including a pit dug yesterday at 2000' on Tincan by an avalanche course. In addition, a Deep Persistent Slab problem remains a concern in the upper elevations above 3000’, and serves as one of the many reason to avoid avalanche terrain today. 

Mountain Weather

Yesterday Center Ridge Snotel recorded 0.6” Snow Water Equivalent (SWE) at 1700’ and the RWIS DOT Wx station recorded (1.13” SWE) at 1000’. Field observations confirmed about 20” of new snow since Thursday when the storm began.  Sunburst Wx station showed strong Easterly winds all day averaging in the 40’s mph with a gust to 92mph last night. Rain/snow line started out at sea level yesterday morning and increased to just below 1000’ this morning.  

Today there is .95” rain (SWE) expected, this translates to another 12-20” of snow in the upper elevations. Unfortunately rain/snow line will continue to rise to 1500’ possibly higher. Strong winds will continue to blow from the East and average in the 40’s mph with gust in the 80-90’s mph. Peak intensity and warmest temperatures should begin later morning through 8pm this evening.

Tomorrow afternoon another front is expected. There’s some uncertainty as to how much precipitation and wind, but temperatures are expected to remain warm. 

*RWIS DOT weather station at 1000’ on Turnagain Pass recorded 1.13” SWE. This weather station is located further North where precipitation is often heavier than then further South in Turnagain Pass. 

**Seattle Ridge weather station is covered with rime and stopped recording wind data at 4pm yesterday (1/12/18)


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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 32  *4  *0.6  57 
Summit Lake (1400') 34  0.1  15 
Alyeska Mid (1700') 32  0.92  48 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 23  ENE  42  92 
Seattle Ridge(2400') 26  **SE  **24  **46 

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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