Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, January 27th 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

Today there is CONSIDERABLE avalanche danger in the Alpine where triggering a storm slab or wind slab 2-3 feet deep remains likely. Loose snow avalanches are also possible in steep terrain. Above 3000’ be aware of older weak layers deep within the snowpack which are becoming very difficult to trigger, but could have high consequences. Evaluate snow conditions as you move up in elevation. Cautious route-finding, and conservative decision making are essential. 

Below 2500’ the avalanche danger is MODERATE where triggering a storm slab 1-2 feet deep or loose snow avalanche is possible. Be aware of runout zones, terrain traps and other people around you.  

If headed to Summit Lake check out teh summary 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.
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.
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
  • TODAY, January 27th, 11:00 am - 12:30 pm: Join CNFAIC forecasters for a FREE hands-on and in-the-snow avalanche beacon practice!! This 1.5 hour informal rescue practice is geared for all user groups. Grab your friends and join us before hitting the hills!! Great intro or refresher! Hosted by the Anchorage Snowmobile Club!  At Turnagain Pass (motorized parking lot) – Look for the blue CNFAIC snowmachine trailer.
  • The Chugach National Forest has opened Johnson Pass trail. Access trail thru open gate and park trucks/ trailers along the road toward the trailhead.  Please keep the turnaround (near large signboard) clear for vehicles to TURN AROUND!

Avalanche Problem 1

Storm Slabs

Almost Certain
Very Likely


Very Large


A sunny Saturday combined with a new load of snow and recent wind loading is a perfect recipe for a human triggered avalanche. A storm that ended Thursday night dumped around 20+” of cold low-density snow and loaded several weak layers (buried surface hoar and near surface facets.)  Several groups reported “whumpfing” yesterday and one human triggered avalanche occurred in the Alpine of Sunburst where a person breaking trail triggered a soft slab that propagated about 30’ wide without incident. A period of elevated winds (15-50mph) last night has been moving loose snow around and loading leeward features and increasing the strength of the slab. Triggering a storm slab today could be big enough to bury a person, and will depend on the steepness and the size of the terrain you are exposing yourself to. Obvious clues like collapsing and shooting cracks will be evidence the snowpack still needs more time to adjust before venturing into bigger and steeper terrain. Hand pits are a good tool to evaluate the slab and weak layers as you travel. Be aware that you may encounter two types of storm snow problems. 

Wind Slab: Fresh wind slabs formed overnight may be shallow or propagate 2-3’ deep on a widespread layer of buried surface and near surface facets. This problem will be more likely on wind loaded features below ridge lines or in cross loaded gullies. This includes the starting zone of the back bowls of Seattle Ridge and the popular SW facing terrain along on the East side of the road.  Pay attention to places where the snow is becoming stiffer and more supportable and avoid steep wind loaded features and unsupported slopes with the classic wind-pillowed shape.   

Storm Slab: Yesterday’s storm snow was loose and poorly bonded and didn’t want to stick together or act as a slab except where it was more consolidated.  Overnight the slab has settled around 5” at Center Ridge Weather Station. This could be enough cohesion to allow the new snow to act more as a slab, even where the slab is very soft. Triggering a storm slab could run farther and faster than expected, which is the nature of cold snow.   Be aware of other groups of people in the same area and practice safe travel protocols. 

Photo on left by Kathy Still of a small slab triggered Sunburst near 3600' and a close-up photo by Chad Saetre of the crown (~24" deep). Your observations are welcomed and apprecated!!!



Note the very large buried surface hoar in a pit at 2700'. This layer was buried with a few inches of snow a few days before the storm is widespread at all elevations. 


Avalanche Problem 2

Dry Loose

Almost Certain
Very Likely


Very Large


Loose snow avalanches ‘sluffing’ is possible on steep terrain features protected from wind. Similar to a storm slab, this dry loose snow could run faster and farther than expected. 

Additional Concern

Deep Persistent Slabs

Triggering a deep slab is becoming difficult, but is still possible above 3000' where a hard slab (3-8 feet thick) is sitting on a variety of weak layers in the mid pack (including buried surface hoar) and old November facets near the ground. The most likely trigger spots are in thin areas in the snow cover, often near rocks, or where the slope rolls over. The Southern end of Turnagain Pass to Johnson Pass is more suspect due to a thinner snowpack where there is a potential for more trigger spots. Remember, this is a 'low probability, high consequence' situation. This issue can simply be avoided by sticking to terrain below 3000’ and is secondary to triggering a storm slab avalanche today. Choosing low-consequence terrain in the Alpine is recommended. 

*** There is very little info in the Johnson Pass and Lynx Creek zone. If you're headed to either of these areas and you observe any signs of instability: recent avalanches, shooting cracks, or whumpfing please send us an observations HERE

Mountain Weather

Yesterday skies were partly cloudy with upper elevations temps in the high teens (F) and valley temps in the upper 20F’s. Ridge top winds were light from the East increasing yesterday evening, 15-30mph, with gusts in the 40’s and 50s mph. 

Today ridge top winds are expected to be light and variable. Skies could range from partly cloudy to mostly sunny and no new precipitation is expected. Temperatures will remain in the high teens (F) at ridge tops and mid 20F’s at lower elevations. 

Cooler temps will continue to influence the weather through the weekend.  Northerly winds are in the forecast for Sunday evening and may be strong at times. There is still talk in the long term forecast for a pattern change mid to end of next week with a possible warm-up with a Southerly flow. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 27  71 
Summit Lake (1400') 20  21 
Alyeska Mid (1700') 25  55 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 19  ENE  15  57 
Seattle Ridge(2400') 22  SE  13  43 

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.

If you have comments or questions regarding CNFAIC operations or winter recreation management, please email
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