Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, March 7th 2016 7:00 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

There is a MODERATE avalanche danger today at the Alpine elevations for shallow wind slabs, sluffs and cornice falls. Wind slabs 6-12" thick may be found just off ridgelines. These could be lingering slabs or fresh slabs from today. At the mid-elevations, the danger is LOW where triggering an avalanche is unlikely. However, there are many glide cracks on easily accessed slopes - being aware of the cracks and avoiding being under them is recommended as they could avalanche on their own accord at any time. 

 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.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
Avalanche Problem 1

It was another spring-like day in the backcountry yesterday with bluebird skies and an opportunity for replenishing vitamin D stores. Today, cloud cover has moved back in but there could be some breaks here and there. We have 1-2" of snow on tap with moderate Easterly winds. This is not enough snow to be a concern on its own but the reactive wind slabs from yesterday, as well as a bump in wind today, will keep wind slab avalanches on the docket. Loose snow sluffs and cornices will also remain on the docket.

Wind slabs:
Wind slabs that we are seeing and hearing about in the Turnagain Pass zone have been shallow 6-10", scattered around ridgelines, and not packing too much punch. However, in the Girdwood Valley and North where more snow fell, slabs are reported to be thicker. 

If you are headed out today, watch for:

1) Stiff snow on the surface of the snowpack
2) Winds actively loading slopes (there may be just enough wind in the forecast to form fresh slabs at upper elevations)
3) Cracking in the snow around you
4) Surface texture and hints that slopes are wind loaded

Cornices!:  Give these a wide berth, wider than you think. 

Sluffs:  Watch your sluff. These are entraining several inches of surface snow and could get quite large in large terrain.

Photo below: Wind slab avalanche triggered by a skier yesterday. This avalanche was between the Magnum and Cornbiscuit ridgelines in an area called Superbowl. Skier was not caught and the slab itself was quite small, 6-10" thick, yet did propagate down the ridge and entrain a bit of sluff as it ran.

Avalanche Problem 2

As long as glide cracks keep moving and breaking up our snowpack we will keep mentioning them. The picture below shows an oblique view of the large cracks on Cornbiscuit's SW face. Folks have been wisely staying out from under them and, in this particular case, putting the skin track on the NW ridge. 

We have not seen a glide avalanche in the Turnagain Pass zone for several days, however we do see these cracks continue to move and open. Limiting time under these, if your route must take you there, continues to be wise.

Photo: Oblique view of the glide cracks on Cornbiscuit's SW face.

Mountain Weather

Sunny skies greeted the many backcountry users along Turnagain pass yesterday. Winds were light from the Northeast on the highest peaks and it was downright warm with temperatures reaching 30F at the upper elevations and 45F along the road. 

Overnight, winds have bumped up slightly (10-15mph from the East) and cloud cover has moved in. There is a very weak disturbance moving over through the day and we could squeak out 1-2" of snow above 1,000' today, with rain below, and another 1-2" tonight. Cloud cover could also break apart is areas, providing for better visibility. Winds are slated to remain moderate in the 15-20mph range from the East along the ridgelines. Temperatures should be warm again, mid 30's at 1,000' and the mid 20's on the ridgetops. 

For Tuesday, another band of clouds and wind are on tap as a low pressure system in the Gulf moves North and begins to impact our region. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35  137 
Summit Lake (1400') 35  44 
Alyeska Mid (1700') 32  108 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 28  NE  17 
Seattle Ridge(2400') 30 

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: Oct 05, 2019 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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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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