Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, March 11th 2017 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

LOW avalanche danger remains in the backcountry at all elevations. Although triggering an avalanche is unlikely, it is not impossible. With today's daytime warming watch for East-through-South-through-West-facing slopes to heat up enough to initiate rollerballs and possibly some shallow wet loose avalanches. Other things to watch for are old hard wind slabs in steep rocky terrain, dry sluffs on steep slopes with soft snow and cornice falls loosening with the warmth. Glide cracks continue to open - limiting exposure under these is recommended.

Remember that good travel habits remain important, even during 'green light conditions'. This includes exposing only one person at a time on a slope, watching your partners closely and having an escape route planned in case the snow moves. 

Summit Lake, South of Johnson Pass and North (in parts of the Girdwood Valley):  A reminder that the snowpack remains thinner in these areas with a poor structure. The chance for triggering an avalanche that breaks in the old weak layers is unlikely but not nonexistent. Read the Saturday Summit Summary HERE.


 Show the Complete North American Avalanche Danger Scale
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1

Yesterday was the warmest day we have seen in almost two weeks. There were no reports of wet loose avalanches or significant roller ball activity but Southerly surfaces were warming up and becoming wet/damp. Today will be another day to pay attention to surface conditions in the afternoon on East to South to West slopes. Steeper slopes and slopes under rock bands will be most suspect. Keep a close eye on any warming taking place on the snow surface. Soft snow still sits on many slopes and roller balls could occur in these areas and a there is chance of shallow wet loose avalanche activity. Slopes with old sun crusts or wind slabs/crusts will be slower to be affected by the warming. 

Other things to keep in mind if you are headed to the mountains to enjoy these long sunny days:

Glide Avalanches:
Glide cracks continue to slowly open above popular terrain on Seattle Ridge and in other areas of the advisory area. These could release at any time, watch for these cracks and avoid being under them.

Wind Slabs:
Old and hard winds slabs are easy to find but for the most part they are locked into place. Steep rocky areas, where they are not supported from below, will be the most suspect zones for someone to pop one out. 

Loose Snow Avalanches (Sluffs):
Watch your sluff. Dry sluffs on steep slopes are probable and are getting larger by the day. And, as mentioned above, wet loose (or damp) sluffs, both natural and human triggered, may occur.

Cornices may start to loosen with the warming - as always, give these monsters a wide berth from above and limit exposure time traveling underneath.

Persistent Slabs and Deep Slabs:
There are various weak layers in our thin snowpack. Buried surface hoar sits 1-3+' below the surface and faceted snow sits in the mid and base of the pack. These weak layers with varying degrees of strength are in a dormant stage due to plenty of time to adjust with a lack of changing weather. Although this means the layers are not producing avalanches, it doesn't mean an outlier can't occur which could cause a large avalanche breaking deeper in the pack. 

Glide cracks North of the uptrack. A series of cracks like these extend out Seattle Ridge to the North at this elevation.


Mountain Weather

Yesterday was mostly sunny and was the warmest day we have seen in almost two weeks. Temperatures rose into the high 20Fs by late afternoon. There was also some high clouds that moved in later in the day. Winds were light and from the Southeast. Temperatures dropped back down into the teens and single digits overnight. 

Today is forecasted to be fairly similar with temperatures in the high 20Fs and light NW winds. Skies will be mostly clear with a few lingering clouds this morning. Tonight temperatures will drop into the teens. Tomorrow the sunshine will continue and temperatures will be slightly cooler. This pattern looks to persist into early next week and then there is a change with a chance for clouds and snow in the later half. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 16   60
Summit Lake (1400')  13 0 0 29 
Alyeska Mid (1700')  22 0 0  56


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  16  SE  3 10 
Seattle Ridge(2400')  17  SE 9  17

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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