Avalanche Advisory

Turnagain Area Avalanche Advisory
Wednesday, January 20th 2016 7:00 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 at and above Treeline today where it is possible for a skier or rider to trigger a wind slab in steep, wind-loaded terrain. As the next pulse of snow and rain moves through today pay attention to changing conditions and active wind loading. In the mid-elevation band (at Treeline), glide cracks continue to pose a significant threat.  Avoiding time spent under glide cracks is the best way to mitigate this particular avalanche problem.

LOW avalanche danger exists below 1000’ 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.
Avalanche Problem 1

The wind picked up again last night and was strong enough move snow. There was snow available to transport from the Monday night storm and a there is more snow forecasted to fall today. This combination of wind and snow creates the potential for wind slabs in steep, leeward terrain that could be triggered by the weight of a person or a sled. Be on the look out for shooting cracks, hollow feeling or sounding snow and stiff snow over softer snow. Remember a small pocket of wind slab in can be very hazardous in high consequence terrain. Cornices and pillowed slopes will help indicate wind-loaded areas.

The winds and new snow will continue to build already large cornices. Avoid spending time underneath or on them. They tend to break farther back from ridgelines than expected.

Practice safe travel techniques in avalanche terrain: ride one at a time, watch your partners, have an escape route planned, park or stop in safe zones and always consider slope consequences.

Wind-loaded slopes and cornices: Tincan Proper.


Avalanche Problem 2

Today at Treeline (the 1,000’ – 2,500’ elevation band) on all aspects, pay attention to and avoid glide cracks. These can lead to glide avalanches that are very unpredictable as we have seen over the past few days. There is no discernable pattern to predict a failure as they tend to fail naturally and on their own schedule. Warm temperatures can trigger them and so can cooling temperatures. Cracks can form and release in seconds or days later or sometimes a glide crack won’t release at all. The new snow has made it harder to see the existing cracks and glide releases in the terrain. 

It is best to give glide cracks a wide berth.  Avoid spending time underneath and if skiing or riding in terrain with glide cracks, try and map them out before your travels so as not to end up directly on top of or inside one.  Remember, when these do fail, they tend to be destructive, failing to the ground and bringing the entirety of the snowpack with them. 

Recent glide release on Wolverine.

Mountain Weather

Yesterday was mostly overcast with a few breaks in the high clouds. Winds were light during the day and picked up overnight into the 20s, gusting into the high 30s.  Temperatures were in the low-30Fs at 1,000’ and mid-20Fs at ridgeline.  

Today will be mostly cloudy with rain and snow showers. New snow accumulation of 1-5 inches possible. Snowline is forecasted to be around 2000'. Winds will be easterly, 15-30mph with stronger gusts. Temperatures will be in the low to mid 30Fs. 

Showers will continue into the evening with a drying trend overnight as the region has a short break before the next wave of precipitation moves in.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 31   0  0  86
Summit Lake (1400')  31  0  0 26 
Alyeska Mid (1700')  32  0  0  26


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 26   ENE 12   39
Seattle Ridge(2400') 27  n/a n/a  n/a 

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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